Nice guy in the street but a freak in the sheets?

...does this man exist? I am a good girl who likes being a bad girl in bed. Why is it when I find a guy I am ually compatible with, they never seem to be great boyfriend material. They like to get down and dirty in the bedroom like I do but the relationship always seems superficial. Then, when I do meet a nice guy with depth and character, the is more light and sensual, not rough and naughy like I like it. Are there any nice guys who are bad boys in bed? I'm beginning to think they don't exist!