Even Evil Has Standards/Playing With

Basic Trope: A bad guy has lines even he won't cross, and detests those who do.
 * Straight: A murdering drug dealer beats a rapist to death with his own S&M paddle, because Rape Is a Special Kind of Evil.
 * Exaggerated: The bad guy has a very long list of things he will not do, to the point that he is ineffectual as a bad guy.
 * Justified:
 * The line in question is rather serious for obvious logical reasons, such as specifically targeting the innocent children of opponents for death (and thus bringing up Pragmatic Villainy concerns).
 * The Villain is a Well Intentioned Extremist and really does have standards and adheres to them religiously, even though he does other horrifyingly evil things in the name of his cause.
 * This also foreshadows the Harmless Villain in the Heel Face Turn.
 * The Villain may be evil, but he's not devoid of humanity.
 * Whenever the villain has an Even Evil Has Standards moment,it's because the irredeemable action is a reminder of pain he's suffered, or the reason he turned evil.
 * The villain commits his misdeeds to get rich, so he gets angry when another villain threatens to destroy the world. After all, there's no point in having illicit money if you don't have anywhere to spend it.
 * Inverted:
 * A hero has a line of things too good for him to consider doing.
 * Some things are just not evil enough for the villain.
 * Utopia Justifies the Means or Well Intentioned Extremist
 * Subverted: Somebody suggests killing a relative of the witness to a murder. The Mob Boss says "No.", and, much later, when asked, proceeds to explain the Pragmatic Villainy reasons for not doing so.
 * Double Subverted: Somebody suggests killing a relative of the witness to a murder. The Mob Boss says "No.", and, much later, when asked, proceeds to explain the Pragmatic Villainy reasons for not doing so. And then mentions that "Even if all that weren't true, it just isn't the proper thing to do."
 * Parodied:
 * The bad guy has a "Evil Etiquette" book, and the Complete Monster is scolded by other villains.
 * The bad guy has no problem with mass-murder, but draws the line at email scams.
 * The murdering arsonist absolutely refuses to jaywalk.
 * Deconstructed:
 * Implication and consequence of extremely amoral acts are shown, to the point that a pragmatic evil code is provided.
 * The bad guy only refrains from what is in his code. Everything else is fair game.
 * Reconstructed:
 * However, the code has several rules that are there simply for moral decency's sake, and are always followed.
 * The rule book is there to keep things in line so things don't devolve into Stupid Evil.
 * Villains with standards last longer because they are thrown into Cardboard Prisons, while Complete Monsters are killed outright.
 * Zig Zagged: Somebody suggests killing a relative of the witness to a murder. The Mob Boss says "No.", and, much later, when asked, proceeds to explain the Pragmatic Villainy reasons for not doing so. And then mentions that "Even if all that weren't true, it just isn't the proper thing to do." And then the guy dies anyway, and everyone thinks it was him, but then he finds and turns in the real killer, who was the guy he talked to. Mob Boss gave the order to kill as a Xanatos Gambit: Whether the witness dies or not, the Mob Boss has an excuse to punish the guy for an unrelated offense, but with the witness' death is not the prefered outcome because they had kids to support.
 * Averted:
 * The Mob Boss doesn't even consider turning on the Complete Monster.
 * Alternatively: Nothing too heinous ever comes up.
 * Enforced: "We want him to be more of an Anti Villain, so we need to give him a code of honor and a moral line he will not cross."
 * Lampshaded: "Don't fear, Bad Guy will not kill you. It would be too evil".
 * Invoked: "As main witness of Bad Guy crime, I suggest you to get pregnant, fast."
 * Defied: When somebody suggests the Mob Boss should turn a Complete Monster into the police, the Mob Boss refuses, pointing out the monster is still good at what he does.
 * Discussed: "We're not dealing with some kind of comic book supervillain here. People, even if they're criminals, aren't going to immediately throw all moral standards out of the window."
 * Conversed: "I heard this movie has some interesting antagonists. Some of the villains are actually shocked when the main bad guy commits particularly heinous acts, and refuse to help the main bad guy any further afterwards. You should go see it!"

Look, I may be a murderer, but I'm not gonna leave a troper in the lurch: here's a link back to Even Evil Has Standards.