I think this sums up many romantic/sexual fantasies. Thrillingly transgressive scenarios can be fun. I don't necessarily see a contradication between indulging fantasy on the one hand, and at the same time having common sense parameters in real life. I've heard some astonishing confessions over the years of what turns people on, some of them seriously twisted, and yet I don't feel particularly shocked. People are psychologically fascinating, and again, what they crave in fantasy doesn't necessarily mean they crave it in reality.

In short, go ahead and fantastise about all the bad boys you like, guilt free. :)