help me understand

i consider myself an intelligent person who can, for the most part, read people pretty well. there are, however, cetain exceptions. take this one person, for example: we'll call him bill. i met bill through some friends about 2.5 years ago (i guess). bill and i have flirted every time we've seen each other (which is not too often), but he's never asked me out. bill has asked me many times (i.e. every time we see each other) if i'm dating someone, and we've had some conversations that would lead the average girl (which i know i am not) to think that he's interested in her. i have never assumed that he feels that way about me (A. b/c i'm not like that, and B. b/c i think i know his type). but clearly there is some attraction between us (give me a little credit here). my question is this: does he know what message he is sending, or could he really be that clueless? based on my limited knowledge of him and his (at times) seeming lack of self-confidence, i would guess the latter. but help me out...could it all be his way of getting the girls? i have heard that this guy has girls fall all over him and even get their hearts broken, and while i see an initial draw (he is fun to flirt with), i don't understand these girls who don't see though his crap. what is it about him? are we women that stupid???

that's it...that's my whole point (or non-point): i don't get it. little help here...anyone, anyone?