Most of the big names in the Justice League are that way. They're good by choice. Batman does dirty stuff, but always for the greater good. Superman respects him for that. It's how they choose to be good that's their differences.

There's a great comic called Huck. At first you think he's stupid until you realize his powers mean he doesn't see the world the same. He chooses to do good, and the entire town respects him for that.