The Schlub Pub Seduction Deduction

""Ah, Power Plant Manager whose name I can't remember, let me introduce you to a universal Sci Fi rule--if you are a geek/schlub, and a hot woman shows interest in you, RUN! Nothing good ever comes of that.""

- a post in The Sarah Connor Chronicles forum on Television Without Pity

Simply put: in fictional bars, attractive women don't normally talk to men who are less than absolute studs. They certainly never flirt or outright hit on such men... So when they do, the audience can reasonably deduce that it's because the women are coldly trying to lead the poor guys to their doom (or at least take advantage of them in a non-sexual manner) with their tricky feminine wiles.

Anime and Manga

 * Happens to Lt. Havoc in the Fullmetal Alchemist manga with his new girlfriend,
 * Subverted, since it doesn't work. The man's a flirt, but he puts his job before pleasure.

Comic Books

 * Played with in Sin City: Goldie hits on Marv, but she's the one who ends up dead. She wasn't killed by Marv, though; she'd seen something someone didn't want her to see, leading her to hit on "the biggest, meanest lug around" for protection. Unfortunately, Marv got drunk and was passed out when what she was running from caught up with her. Cue Roaring Rampage of Revenge.

Film

 * Mystique and a prison guard from X-Men 2. Sure, she drugged and injected him with iron, so that Magneto could rip it from his blood and escape, but he got to make out with Rebecca Romijn. Lucky bastard.
 * This trope is basically lampshaded when Magneto tells the guard that he should never trust a pretty woman - especially one who's interested in him.
 * The alternate ending to the (narmful) remake of The Wicker Man.
 * This happens several times in James Bond movies.
 * In Goldeneye with Xenia Onatopp, the woman who sexes a Canadian officer to death to steal his documents.
 * In The Living Daylights, a humorous scene involves a mannish, overweight woman with large breasts seducing her boss by shoving his entire head inside said voluminous bosom. After Bond leaves, she throws him back and snaps, "What kind of girl do you think I am?!"
 * A genderswapped version appears in the 2009 movie Duplicity -- hottie Clive Owen chats up a frumpy woman, as a ploy to get her to take him back to her office in order to access the company's computer network. His female colleague is not happy about this tactic, despite the fact that she pulled the same stunt in their first meeting, in order to steal some files Owen was carrying.
 * Amusingly Owen had to put more effort into it than normal for the trope. Not only was he charming and good looking but he also pretended to be from the same small town and even implied (or maybe outright stated I forget) that the woman and he knew some of the same people. I guess men are easier to fool into thinking you like them? Or women are dumb enough to automatically think anyone from her home town is a good guy? Either way there are some Unfortunate Implications here.
 * She didn't think he was a good guy because of their shared home town, so much as because he was posing as a doctor working with a Doctors Without Borders-like foreign aid organization. Being from her hometown was gravy.
 * In Sneakers, the group of shady security experts arrange a date between an employee of the Big Bad (a geeky computer expert) and their leader's ex through an early dating site in order to keep the employee distracted and out of his office while they break into it. The second the Big Bad hears of this he incredulously says "A computer matched him with her?" and locks down the building, knowing the good guys are up to something.
 * Enchanted. Narissa on Nathaniel. Nathaniel begins to realize he's a dupe when he sees a soap opera variant.
 * This trope shows up in several Mystery Science Theater 3000 films.
 * Space Mutiny. Lea in a Squick moment. Although Lea's attractiveness is somewhat informed. The riffing, naturally, lampshades the hell out of this: "You know, the last eight times this happened, the woman just wanted to get away!"
 * This is roughly half the plot of High School Big Shot; the popular Betty seduces bookish anti-hero Marv to get him to write an essay for her; the plan backfires and costs Marv his chance at a scholarship. This pushes him over the Despair Event Horizon, driving him to plan to steal a million dollars of Mob money kept at the warehouse he works part-time at. All to get Betty's attention. It doesn't end well.
 * Seen in Angels Revenge. Especially Egregious as they're dressed in bikinis on a ridiculously cold, foggy day on a deserted beach.
 * And again, in Operation Double 007: the Bodyguard Babes of the Big Bad expand this trope into a scheme to steal some Applied Phlebotinum from a military convoy in the middle of the deserts. The skunk outfits play a vital role... somehow.
 * And even more, with Watney Smith and the Queen in Outlaw of Gor.
 * This happened more than once with The Three Stooges, typically to Curly.
 * Directly lampshaded by a girl in She's the Man, who tells a guy, "Girls with asses like mine don't talk to boys with faces like yours." Also inverted, in that she gets dumped not only by her boyfriend, but by her boyfriend's sister.

Literature
"When approached on a sexual level, covert operators should remember that they have not necessarily been found attractive beyond the moon and the stars but rather that the person making the approach is allied with the opposition and attempting to subvert, to maneuver into a life-threatening situation, or to provide the opposition with blackmail material. In any event, until a life-threatening situation occurs, it is recommended that operatives pretend to be seducible. Interesting intelligence has been produced in such situations."
 * The Best-Case Survival Handbook (a parody, of course, of the Worst Case Survival Handbook series) has an entry on (paraphrased, since I don't have it on me) "What to do if you are approached by a fantastically beautiful woman who invites you back to her hotel room for a night of athletic, no-strings-attached sex". It goes something like "Run. The only person this actually happens to is James Bond. And she always puts a scorpion under the pillow or something."
 * Amusingly inverted in Quantum of Solace (the film):
 * The second book of the Sten series invokes this when the beautiful younger sister of a major political player comes on to Sten. He recalls a training manual which stated:


 * This isn't quite a straight example, however, as Sten is noted to be attractive enough that women often enough do approach him just for sex or romance.
 * Admittedly, out of all the times the woman comes on to Sten out of the blue or arranges a meet-cute, there is exactly one of them who approached him without ulterior motive. All of Sten's other non-betrayal relationships involved him making the initial pursuit, and even some of those turned out to be traps.
 * Furthermore, it turns out to be a subversion. Her brother told her to seduce Sten, but she's not interested in helping her Jerkass brother, and genuinely interested in Sten.
 * A short story by Spider Robinson involved a painfully awkward and very unattractive computer geek being approached by a memetic sex goddess. She puts a crown on his head then takes him back to his apartment for all sorts of sex saying, along the way, "Hurry, my lord, I'm positively dripping" while other bar patrons stare at him. After lots of awesome sex,

Live Action TV

 * Catherine Weaver and the power plant manager in The Sarah Connor Chronicles episode "Goodbye to All That".
 * Farscape inverts the trope. In "Fetal Attraction" handsome John Critchton hits on a much older Sebacean nurse with access to Aeryn. However she's suspicious and only relents when he throws in a cure for a disease running rampant on the station as well. That being said, he played the horndog well enough that when he's captured, he's able to bluff a species that is mildly psychic that the reason he took Aeryn is because she was prettier than the nurse and he was planning to have sex and babies with her...which was technically the truth, but not the whole truth.
 * Averted so far with Dr. Keller and Dr. McKay in Stargate Atlantis.
 * No result as serious as death, but you know when Veronica flirts with Phil in Better Off Ted you know that she has ulterior motive. Turns out the 'autograph' she wanted was on a waiver promising not to sue the company.
 * Played with on The Shield. The Strike Team is tasked with investigating a series of robberies at a strip club - the girls proposition men for alley sex, but one of the girls has an accomplice who attacks the johns. Vic tries it, picks "incorrectly" and gets a blow job. Shane tries it, and gets a tire iron to the head.
 * Sydney Bristow did this to bad guys in nightclubs all the time.
 * Rick Castle gets seduced by an actress who wants a part in his movie. When he confronts her with the possibility, she breaks down in tears and asks "How could you? Do you know how hard it is for a woman in Hollywood?" leaving him feeling bad. Of course, she was just after a part. He ended up not rescinding his recommendation because she was a good enough actress to fool him into thinking he'd really hurt her with the accusation.
 * Lampshaded in The Drew Carey Show episode "The High Road to China". Drew awakens and finds himself stranded in China, on the Great Wall, with no money and without his passport. He thinks back to what he can remember "How could this have happened? I was at the airport, I was waiting to go to Winnepeg on a conference, a beautiful woman asked to buy me a drink... Oh, what am I? Crazy? Why would a woman ever buy me a drink?!".
 * Provenza and Flynn really should have figured this out a lot sooner in The Closer episode "Layover". Two stewardesses start dating them as a cover for their drug smuggling activities.
 * Used numerous times in Hustle.
 * White Collar has a gender-flipped version, where Neal Caffrey seduces a woman in a bar to find sercret information on his boss. (Of course, she's not quite as unattractive as male examples usually are.) Similar tactics to this are a normal part of Neal's arsenal.
 * Sarah Walker in Chuck once seduced a geek who had developed a secret weapon. Of course, she also attempted this with Chuck, although not in a bar, but in the Buy More, so the CIA could get their hands on the Intersect.
 * Fiona from Burn Notice does this many times, but it's also subverted on a few occasions. For example, in one case she approaches a professional safe cracker with multiple arrests for drunk driving and tries to get him liquored up so he'll be arrested again and his team will be forced to call off the job they're pulling. Due to the fact that Fiona is way, way out of his league, comes out of nowhere and then starts proposing toasts to them with expensive champagne, he figures her for a High-Class Call Girl and leaves.
 * Parker does this to a mark "The Fifteen Minutes Job" in order to sell the con (no one would look twice at him if he hadn't gotten some minor media attention). She didn't even stab him!

Video Games

 * The fundamental premise of the video game Catherine.
 * Parodied in the Mark of the Assassin DLC for Dragon Age 2. Tallis repeatedly uses this trope in order to get a key. Despite her claims that she's quite good at this, she keeps failing because the target a) doesn't have the key or b) isn't interested in her. She eventually gets so frustrated that she makes Hawke have a try. Hawke can seduce the target as expected (which works equally well regardless of Hawke's gender)...or Hawke can just knock the guy out and take the key off him.
 * Certain perks in later Fallout games (particularly Fallout 3 and Fallout: New Vegas) allow the player to do this by bypassing skill checks or bribery options to get information.

Web Comics

 * Played with in Spinnerette: Sahira attempts to seduce a guard in order to allow Heather time to break into a lab, only for him to lampshade this very trope...then give Sahira the video the girls were after in exchange for a legitimate date.

Western Animation

 * In The Critic, Jay Sherman falls in love with a woman who stars in a really bad film. He says the movie is bad (Jay is a film critic) and she leaves him.
 * She fell in "love" with him specifically so he'd give her movie a good review. What's really sad for him, is that he and his family and friends actually all suspected this at first, only for her to convince them otherwise. In the end, he's torn about giving her a bad review because he's fallen for her and doesn't want to hurt her feelings or career. He comes home expecting her to be furious, but she's just gone instead.
 * Averted by Jeremy Hawke's sister, who's a hottie who happens to be attracted to needy losers. Her last boyfriend before Jay was Larry "Bud" Melman. After Jay? A hayseed who needed his pants zipper drawn - while wearing the pants backwards.
 * Played pretty straight in another episode where Jay is seduced by the woman working the projector. She has the sexy eyes that lure him to the booth for some loving, but she turns out to be nuts: kidnapping him so he can personally review every movie for her (she was sick of being embarrassed in front of friends by her inability to distinguish the quality of films).