Sniff Sniff Nom

""A plane crashed here.""

- Cordell Walker after applying this trope to dirt on Walker Texas Ranger

A character, coming across some unknown substance, will always smell it with a puzzled expression, then hesitantly taste it. It is almost always something that most people would definitely not want to put into their mouths, but the character somehow decides that this is the best way to determine what it is, because he might just want to know, "Is It Something You Eat" for himself.

May lead to It Tastes Like Feet or ~I Ate What?~ Fingertip Drug Analysis and The Ketchup Test are subtropes.

Anime & Manga

 * Alice of Pandora Hearts does this with a lot of things, including flowers and a pet bird.
 * In the Patlabor episode "The Tragedy of L," Captain Gotoh tastes a sample of what appears to be blood (but isn't). This horrifies everyone else.
 * Captain Britten is the butt of a similar joke in the animated version of Dominion Tank Police. After his first taste he assumes it to be blood plasma; Lovelock is forced to tell him that it's urine.

Commercials

 * In a Quattro ad, a tow-truck driver laments the fact he's never towed a Quattro in language reminiscent of a frustrated hunter. Like a hunter, he checks the snowy ground for (tire) tracks, even taste-testing the snow in his search.

Film

 * In Pi, Max tastes a suspicious melted computer part.
 * In Charlie and The Chocolate Factory, young Willy Wonka seems willing to taste anything as a potential candy ingredient, including mashed caterpillars and the green goo left on his machete after cutting a giant mosquito in half.
 * The B-movie The Stuff begins with this trope: a miner, walking out in the woods at night, stumbles upon a mysterious white fluffy substance on the ground. Guess what? It's delicious!
 * The exterminator from the movie Mousehunt does this with mouse droppings. He can tell a disturbing amount about the mouse from this...
 * In the obscure German movie The Ogre, noone but Hermann Göring shows the protagonist how to do it with deer scat. Squick.
 * A gag in Young Doctors In Love involves one character pretending to analyse urine by tasting it. Another character ends up tasting it for real.
 * In Bill and Teds Excellent Adventure, Ghengis Khan sniffs and tries to take a bite out of a baseball bat. When he realizes the bat is inedible, he tests its use as a weapon.
 * In the sci-fi comedy "Paul", a Man in Black hot on the trail of an escaped extraterrestrial searches for clues at the scene of a car wreck and comes across a puddle of unidentified liquid. In closeup, we see the agent's hand dab a sample of the stuff and lift it off screen. After a beat, he sputters and violently spits it out. It turns out
 * In an odd moment in The Bobo, Juan (Peter Sellers) grudgingly takes Olimpia (Britt Ekland) to a posh, dignified fur salon. When a server comes by with a silver tray of tea and wafers, Juan makes an undignified grab for a fistful of wafers. Everyone freezes, and, acknowledging the gaffe, he slowly draws them to his nose and sniffs them suspiciously before taking a bite.
 * In the Coneheads movie, Beldar sniffs and eats the miniature soap as he and his wife stay at a motel during their first visit on Earth.

Live Action TV
"Doctor: A-positive, with just a hint of iron."
 * House has cheerfully tasted a homeless woman's old vomit in order to diagnose her.
 * As well, he later snacks on homemade tomato sauce, currently being tested for botulism.
 * Several seasons later, he forces a guy in an Antarctic research station to taste a woman's urine in order to test it to determine what's causing the Patient of the Week's unconciousness.
 * Truth in Television, as taste-testing of human urine was done by Real Life physicians before chemical assays for glucose and other substances were developed. (Diabetes mellitus got its name because it makes a person's urine taste sweet.)
 * Jubal Early, the bounty hunter in the final episode of Firefly, sniffs and then licks part of the railing support on the stairway to the cargo bay of a spacefaring equivalent of a rusty old tramp steamer.
 * The Tenth Doctor is fond of this. He's even licked a piece of Dalek tissue.
 * Ten does this with a blood sample in "The Christmas Invasion".


 * And the Eleventh determined the age of a shed by licking its wall.
 * It must be a Time Lord thing, as Romana once used the same technique to identify concrete.
 * Going by fanon, Fraser does this in Due South.
 * In the pilot, Fraser apparently tastes some mud in a witness' garden before confronting her about harbouring a criminal. Vecchio concocts an elaborate theory about how the crucial information might have been gathered from the mud, before Fraser reveals that it was all just a bluff to make the witness think he knew something he was in fact guessing. Did he really put mud in his mouth? It depends on one's interpretation of just how far Fraser is willing to go for a convincing deception.
 * Jim Ellison does this in The Sentinel. Justified due to his heightened perception.
 * Gil Grissom does this to a human bone in an episode of CSI.
 * Well, it's actually a rock, which he can tell by it not sticking to his tongue like a porous bone would. Still pretty nasty, though.
 * In Crime After Crime the coroner detects PCP by smelling an organ of the deceased (not tasting it, though).
 * On Oz and James Drink To Britain, James May does this with a puddle of something that has leaked from the wheel well of the mobile brewery (a.k.a. caravan) he and Oz are traversing Britain in. The puddle turns out to be James' own homebrew beer.
 * Walter has a habit of doing this on Fringe. Subverted in that he often knows what it is (for example, some food he's left lying around the lab or gotten on his clothing) or at least knows it isn't what the other characters think it is (as when he waits until after tasting the contents of an urn to point out that he knows it isn't human cremains - presumably because of the color and because it was actually ashes, while cremains technically aren't).

Mythology & Religion

 * Shen Nung Shi, the Chinese mythological tamer of plants, who was said to have tried eating every kind of plant available to see which ones were beneficial and which poisonous.

Newspaper Comics

 * Calvin occasionally does this with his mom's cooking.

Video Games

 * In The Elder Scrolls, you can eat alchemy ingredients to figure out what they do, inflicting a weakened version of that effect on you in the process.

Webcomics

 * There's an early scene in The Hotel Fred where a character licks a message on a mirror, and announces that it's guacamole.

Western Animation
"Hermes: It looks like toxic waste... smells like toxic waste...
 * Used by Kowalski of The Penguins of Madagascar.
 * In the Futurama episode "Leela's Homeworld," Hermes Conrad uses this to determine whether the bright green waste product being generated by the Professor's latest invention is toxic waste.

Fry: What's it taste like?

Hermes: (dips finger in barrel and licks it off) Delicious fig pudding! Ooh, that's good! ... But a distinct aftertaste of toxic waste!"

"Katara: You just recovered from the cactus juice and now you're licking something stuck on a cave wall?!
 * In the episode "Love's Labors Lost In Space" the guy Amy's parents try to set her up with does this with the lobster bisque. He's not trying to figure out what it is; he's just gross.
 * In the first episode of Gargoyles, while locked up in the rookery with Brooklyn, Lexington, and Bronx, Broadway does a textbook example to some slime he finds. His brothers are understandably disgusted and concerned (that he might eat them).
 * Sokka from Avatar: The Last Airbender does this to the moss covered walls of a cave.

Sokka: I have a natural curiosity."

"Jake: Heh. That's adorable!"
 * Most of the dishes cooked by Tino's mom on "The Weekenders" get this treatment.
 * Adventure Time: Finn tries to show Susan Strong how to toast marshmallows. Susan tosses away the marshmallow and gnaws at the stick.

Web Videos

 * In the video "Troy Shaves His Face," by You Tuber troyhasacamera, creator of Marble Hornets, Troy takes the shaving cream, sniffs the brush, tastes it, and proceeds to cover his whole face in it. In a bloopers tape posted on his Facebook profile, while first tasting the shaving cream, he almost pukes.

General

 * Cops taste testing for drugs, Seen It a Million Times, both in movies and on TV. The writers Did Not Do the Research, or maybe that's how they check their drugs. See: Fingertip Drug Analysis.

Real Life

 * Dogs
 * Rats are hard to poison because, when they discover something unfamiliar that might be food, just one or two members of a colony will invoke this trope. Then the other rats all sit back and watch to see if the taste-testers die or not.
 * Truth in Television: Most newborn children stick things in their mouths when exploring the world around them.
 * Subverted in that this is more of a way for babies to feel an object than taste it. At that age, the mouth is more touch-sensitive and coordinated than fingers.
 * Show of hands. how many people will lick their least favorite/ odious food when ordered to "taste it".
 * If you get the opportunity to do so, watch a ceramicist or a geologist attempt to identify an unknown material without tools. Chances are, they'll eye it closely, hold it up to the light, scratch it with their fingernail, give it a healthy snort, and then stick it in their mouth. They do this not to determine its edibility, but rather, its porosity and strength. Porous materials tend to stick to the tongue, and it's easier to precisely test relative pressure with your teeth than with your fingers. Also, some materials really do have a distinctive taste. So it's a perfectly rational thing to do with an unknown object, just a little gross and requires a little training.
 * It is also used to measure grain size, as it is easier to distinguish between silt and clay by how it grits against your teeth than how it feels under your fingertip. Certain minerals also have a distinctive smell if made warm and damp by exhaling on them.
 * This is also a way to tell an authentic pearl from a fake. A real pearl will feel gritty on the teeth, whereas a fake will be smooth.
 * Sharks examine everything with their mouth due to a lack of hands. Tiger sharks often take the cake in this as they eat just about anything. This is little consolation to a surfer after the Great White decides he's not a seal.
 * This is standard operating procedure for many animals with keen noses when faced with something they think might be edible.
 * It's par for the course if you're an archaeologist. The easiest way to decide what sort of ceramic you're holding it to put it to your tongue - terracotta sticks, but the others don't. The same goes for bone, though due to the fragility of the bone after so much time in the ground, it's usually tapped against the teeth instead to see what sound it makes.
 * VERY averted for chemists. While smell is often used as an indicator of chemicals, and on very rare occasions, taste, it is heavily discouraged when working with unknown chemicals, and many people have died or been injured heavily by tasting chemicals. On the other hand, accidentally tasting chemicals has, amongst other things, brought artificial sweeteners into the world.