Vampire: The Masquerade has several levels of standards, especially considering the players are playing corpses repeatedly engaging in what is essentially rape (and cannibalism.) Most clans despise the Sabbat (for being Ax-Crazy nutcases with seemingly no regard for the Masquerade), the Giovanni (for being incestuous necromancers) and the Setites (for being dealers in generic sin). These in turn despise the Ba'ali (for being worshipers and servants of powers wanting to end existence). And certain sub-factions of the Ba'ali despise the other subfactions.
The Ventrue (in the Old World of Darkness) are the Blue Blood rulers of the Kindred, and the highest enforcers of the standards expected within the Camarilla.
Vampire's Humanity mechanic allows players to invoke, invert or subvert the trope any way they choose. But they can never really avert it because of the long-term gameplay impact, which reinforces the trope as an essential theme to the game. "Monsters we are, lest monsters we become."
In some ways, the Virtues of Compassion and Self-Control mimic this. Low Compassion or worse, its opposite, Conviction means you can do Horrific things without even suffering the slightest pang of guilt, but high Self-Control keeps the Evil in check - if you had low Self-Control you'd be Ax-Crazy, leaning towards Blood Knight .
Many of the more inhuman moralities have this trope in full effect. Two examples would be the path of Lilith and the path of the night. Those on the path of Lilith believe that pain is a good thing, they will happily kidnap and torture people for no better reason than a passing kindness of making them more jaded and realistic. Murder to a lilin is seen in exactly the same light as to a follower of Humanity; "dead mortals feel no dread". The path of the Night views vampires as agents of hell. They choose a victim, investigate them until they find a sin, however minor, then torment and traumatize their victim with the aim of making their life a living hell. Emphasis on living once again, killing is still wrong.
The Guide to the Sabbat sourcebook encourages players to play Sabbat characters who go about murdering, raping, torturing, and generally raising Hell, metaphorically at least. But if you literally try to raise Hell...the book mentions in several places that demon summoning is a Bad Thing, the GM is under no obligation to allow the players to do it, and if they do, the GM should be willing to drag their characters off to Hell on a whim.
And in-universe, the Sabbat, who make a point of being pure and utter monsters, with no regard for human life and no care for anyone's safety, will haul you out of your haven and throw you into acid if they find out you're messing around with demon-invoking.
Now (2011) the Grey Knights have an Inquisitor who will happily call in orbital strikes on his own men. It makes the shot perfectly accurate. Then again, given that the supposedly holy Grey Knights butcher nuns and use their blood as a holy ointment in this same codex, the "good" and "pure" seem far worse than the evil.
Khorne, the Chaos God of rage, murder, and general Ax-Crazyness will fuck you up if you try to present him skulls of defenceless people. Although this is less because he has standards and more because he wants skulls of worthy foes (trying to present him a bunch of baby skulls would be cheating). He doesn't seem to have any problems with the actual killing, though.
He does, however, loathe the use of trickery and deception. As a result, he's the only Chaos God in Fantasy whose followers cannot use magic.
The same goes for 40k, none of his followers can use psychic powers (even his daemons) and need to resort to more conventional (in comparison. A plasma cannon is anything but conventional otherwise) methods of dealing ranged damage.
Sadly Khorne has been Flanderized, he doesn't really care who gets slaughtered anymore, though he still doesn't like Sorcery, Trickery, or anything else that is considered "Using methods that do not rely upon one's own skill set".
Part of said Flanderization is the fact that many people consider Khorne worshipers to eschew ANY ranged combat, except maybe "randomly fire a pistol into the people you're charging at head first". They forget that Heavy Bolters and Autocannons make a *lot* of blood spill; it's not the ranged aspect that bothers them, but the fact that such weapons require little actual skill beyond "hold it steady as it turns people into paste." The paste is perfectly acceptable.
The Redemptionists, a splinter sect from the Imperium dedicated to burning things even remotely heretical, are so deranged that the Imperium is frightened by them.
This crops up any time the followers of opposing Chaos Gods butt heads. For instance, Tzeench will have no compulsion against setting up schemes that cause untold billions to suffer near-eternal agony if it fosters positive change for (at least some of) his plans, but cannot stand the way that Nurgle just makes everything rot and fester and corrode without any greater end-game.
The Necrons are basically genocidal Undead robotic skeletons. But even they're creeped out by Necrons known as Flayed Ones.
In the Horus Heresy tie-ins, even the Iron Warriors - who committed genocide on their home world to suppress a rebellion, and who are among the most ruthless and bitter siege troops in the setting - think the Emperor's Children have become badly fucked-up and a disgrace, and they are appalled by Mad Doctor Fabius Bile's...experiments on other Space Marines.
In the Eberron D&D setting, evil is not dependant on one's personality or goals, but rather, on how much one is willing to compromise. The queen who wages a bloody war to conquer the kingdom is good while the king who tries to maintain peace and security is evil. Why? Because she has standards; she wouldn't stoop to underhanded assassination plots, for instance. The king? He'd throw puppies into a woodchipper to achieve his goals. Evil does not have standards in Eberron.
Many of the big-name villains of the Ravenloft setting have standards, even if their other crimes overwhelmingly outweigh them. Strahd von Zarovich, though he preys upon them himself, vigorously protects his Barovian subjects from outside threats; Dr. Mordenheim has treated the injured even if it didn't advance his research to do so; Azalin takes his obligations as a king very seriously, despite the fact that he despises his kingdom.
There are also different degrees of evil among the darklords. Azalin has nothing but contempt for the cruel tyrant Vlad Drakov, the lord of the neighboring Falkovnia; same with the all the darklords of the realms who border Falkovnia, actually. And the ironic part is, Drakov has no supernatural powers at all. He's fully human. But his cruelty is greater than almost any darklord who does.
In the Pathfinder setting, devils are bent on dominating all that is, bringing order to the universe through tyranny and treating mortal souls as tools, slaves, and currency. Demons enjoy desecrating the flesh and warping the souls of mortals, seeing them as playthings. Both devils and demons will put their differences aside and work alongside angels to stop daemons, who only want to eat and destroy mortal souls.
Rovagug, God of Omnicidal Mania, tends to invoke this among the other gods. Asmodeus (God of Tyranny), Zon-Kuthon (God of Envy, Darkness, and Loss), and Lamashtu (Goddess of Madness, Monsters, and Nightmares) are opposed to his being released, largely because hey, not even they benefit from the end of the world.
This is how some people view the Lawful Evilalignment in Dungeons & Dragons. He may kill babies, assassinate kings, and plot to take over the world, but many an Lawful Evil villain will never engage in wanton slaughter to no purpose and will never break his word. That being said, there is nothing to prevent a Lawful Evil from engaging in Pragmatic Villainy and finding minimal pretense to do the above ("I won't slaughter these villagers For the Evulz, I need living space for my more important countrymen"). Furthermore there is nothing to prevent the Neutral Evil and Chaotic Evil characters from having standards themselves. And the biggest flaw of the Lawful EvilEven Evil Has Standards view is that Devils, the literal embodiments of Lawful Evil pre-4th Edition, do all these things without the need for standards.
The Drow, the infamous Evil Counterpart Race of the Elves and Eladrin, are brutal, fascist conquerors whose society is based around lies, deceit and betrayal, is prone to brutal infighting, and lives by the unpredictable whims of their batshit insane goddess. And yet, even they are disgusted by the horrifyingly insane Derro, so much that they're willing to put aside whatever evil plot they're currently concocting to put a stop to the Derros' own plots.
Numerous examples occur in the Elder Evils guidebook, where evil beings side with the heroes to oppose the Eldritch Abomination featured in the scenario, seeing what the creature is doing is something they cannot allow. The most extreme example is given in the backstory for Zargon, which claims that Asmodeus (the setting's version of Satan, for pete's sake) sided with the forces of good to halt the Elder Evil's first rampage. (The book does suggest, however, that this may have been at least partially a case of Pragmatic Villainy on Asmodeus' part, seeing as Zargon was the former ruler of Hell who he had overthrown, and he did not want the guy around.)
Scion has this in regards to Loki. He initially backed Hitler's rise to power in Germany in the hopes that a united Europe would allow him the power needed to stave off Ragnarok (it makes sense in context), but he was unaware of the Holocaust and would not have condoned it. After World War II, the Nazi high command faced the greatest punishments Hel could deliver... but Hitler's soul never appeared in the Underworld.
The authors do note that while some gods aren't exactly the nicest of individuals, they still do care for humanity on some level. Even the most bloodthirsty of the Aztec pantheon would not callously slaughter huge numbers of mortals For the Evulz. This is what sets apart the Titans and the darker Gods.
In Rifts, the Obviously Evil Coalition States is lead by Emperor Prosek, who will cheerfully plunge his nation into pointless, horrific wars for the sake of power. He is absolutely ruthless when it comes to destroying non-humans and magic users. He even has a facility used to create mutant animals to be used as canon fodder. However, genetic experimentation on humans is strictly forbidden.
The "Aberrant" character alignment is essentially this — an Aberrant character is unambiguously evil, but at the same time follows a strict personal code of ethics. They may (for instance) kill without a thought, but never without reason, and are disgusted by characters of the "pure evil" Diabolous alignment.
In The Dark Eye, those who forge a pact with the demon lord of tyranny and vengeance are despite their evil will direct enemies of the servants of the nameless god. The demon lord's demon subjects may even demand this attitude of their human "masters" no matter how well they are controlled.
Another Dungeons & Dragons example; when 4e pared down the Character Alignment system, this became the primary way of differentiating between Evil and Chaotic Evil. An Evil character can still be a complete and utter monster (see the Devils mentioned above), but usually their vision for the world is relatively tolerable. A Chaotic Evil character, on the other hand, has such horrific goals (however loosely applied) that even Evil characters are horrified by them. There's a reason the main holders of the alignment in 4e are Demons and Slaadi. This means a Chaotic Evil villain is the kind of thing that can make Good, Unaligned and Evil characters team up to beat its head in.
The Al-QadimDungeons & Dragons setting encourages this trope with regards to honour, citing examples from the Arabian Nights and Arabic folktales in which a variety of murderers and thieves hold the Sacred Hospitality of taking salt to be an unbreachable code.