Why is the society evil? Is it because some members of that society are being abused? If everyone's happy then it gets a bit hard to argue that it's an evil society.
There is a reason I placed evil in quotes. But every member of the drow society that worships Lolth is being abused, though Drow don't always feel like they are being abused, some of these things are just normal to them.
Why is the character evil? Can they adjust to living in a "good" society where you'll be more successful by being nice and friendly?
On a philosophical level evil is subjective, in a more conventional undrstanding an evil character is someone who doesn't have a problem with improving their well being at the expense of other peoples well being.