No, not the heroes on Harleys (though, of course, we love them too).
I mean villains. The bad guys of the book. The evil doers, the ones who get in the way and mess everything up. The men (and women) we love to hate.
I'm currently in the process of trying to make my bad guy badder, less of a pushover and harder to figure out. I have ideas that go above and beyond where he started out, but in second guessing myself I've created an endless loop. If I think he's nasty, as I did in the first place, will he be nasty enough for a reader? If he's nasty enough for a reader, will I think it's too much? If he's not bad enough, will I kick myself eternally, thinking 'I could have gone a step farther'?
Probably. That's the way these things go.
But I do wonder: Do you, as a reader, want to hate the villain? Do you like to like the "bad boy"? Would you prefer to know a lot about him, or be a shadowy figure in ther corner of the page? Other options?