As a GM I generally don’t care if my players fit into overly simplistic molds like “good” or “evil” provided their character is an interesting person with both a reason to work with the group & the group’s characters have reason top believe that he or she is better & more useful with them than elsewhere (or dead). By extension, I don’t much care if the group wants to think they are evil, actions have consequences & it would be dam,=ned inconvenient if this nifty world/plane of existence/etc you keep your stuff & servants in were to get destroyed.
Running an evil game is actually easier than a game filled with peace & love hippies who want to help everyone & never consider hurting anyone because they tend to plot and scheme together towards a goal more defined & consider consequences beyond " lets massacre our way to stopping evils!"
As a player, I work to make sure my characters are loaded with strings GM’s can easily attach hooks to even when those strings look all tangled up in knots of personality & motives at first glance, personality & motive are strings in their own right as well. A warforged Juggernaut who acts badly towards fleshbags but goes out of his way to work with the “unit” of fleshbags he’s assigned himself to after seeing horrible things that need stopping show up around them even while outwardly looking to begrudge their incompetence & “obvious” curse (everyone was frequently in tears from laughter during those games) because he knows he has -10 sense motive & needs them to keep that L0 commoner from using diplomacy to take all his stuff for some magic beans or a LE rogue who may or may not have a devil for an ancestor who uses bluff to convince the “oh my god people will think I’m more legitimate if I can keep this paladin sitting across the table” that sneaking out of Baddie McEvil’s house through a back exit rather than trying to reason with the torch & pitchfork wielding mob at the door angry about poor dead baddie mcevil is the best course of action because thoise people are innocents without all the facts wanting blood & things would probably just break into a fight to the death until they’ve had time to cool off. That fight would gain nothing of value & could cause his newfound paladin trophy/sidekick to lose value as a prop by losing his standing as a paladin is perfect justification for walking close enough to the paladin’s ideals when he’s looking & using a spare braincell to make sure he doesn’t cause the fall. are both examples of characters I’ve played in the past as a player