Alright, lemme explain something here. I have actual definitive terms on this.
Being an ass is like being a jerk or a prick, or a dick and dumbass. Ya following me so far? Now, there is a term out there that I don't necessarily associate with being an ass, though sounds like it should, and that's being an asshole. What do I mean? I'm referring to the right kind of badass who ain't a hardass, but rather he has class and style. You wouldn't call him an ass, because despite his attitude, you like the way that he is. You could call it a special type of maybe a fluke of nature, but there's no beating the asshole who's like Denis Leary. You gotta love 'em for what they got, 'cause they gots moxie.
That being said, I'm a villain myself. A proper villain, as opposed to just an evil bastard. THAT kinda' guy is a real ass, in my opinion.