I've dated two 'good guys' like yourself. My current bf does not really fall under that category, and I often find myself wishing he was more like my exes. Ah well, I don't think it's going to last anyways.....and when it does end, I will be going back to my 'good guy' preference.
Don't feel bad about not wanting to be a sleazebag. There's enough of those guys out there in the world, and 'nice girls' get tired of them after dating a few and realizing what losers they are. That means more 'nice girls' for you in the end. I think that's worth it, don't you?
Live as if you were to die tomorrow. Learn as if you were to live forever. - Mohandas Gandhi