My wife Wendy loves to discuss this topic, as she loves to throw her Masters in Anthropology expertise in there. Although I do have to agree with some of what she says. She tells me that under basic instincts, women are drawn to the need of having a strong provider (good looking, confident, successful, strong-willed, decisive)... unfortunately somewhere in the mix they are mistakenly drawn to loud, abusive, egotistic arseholes because they give that hard self-confident signal that cuts right down the basic instincts. Hence being drawn to the "Bad boys".
I don't know if she's right or wrong with assumptions, but it has a ring of truth to it from my experiences. Nice, shy, sensitive guys don't seem to hit that instinctual hot-spot from my observations in my life, despite being good-looking or not. When I was in my 20's I had a long string of being crushed for being a nice guy, and finally one day I snapped and said to myself "I'm going to be like the rest of the military arsehole guys I know, go out, find the best looking girl I can at the club, treat her like shyt, take her home, and throw her out in the morning". I did, found the hottest girl at the club, was a cocky son-of-a-bytch, even abusive in my conversation, and she jumped all over me. The more I was a jerk and tried to get rid of her, the more it seemed to turn her on. I'd tell her to go away and I never wanted to see her again, and she'd stalk me like a fanatic and wind up in my dorm room naked waiting for me. Took me three months to finally be rid of that crazy woman. But it wasn't me, nor who or how I was. I felt horrible for the whole fiasco and weirded out by how freakishly this drop-dead gorgeous girl latched on to me and behaved. Finally years later I met a woman who liked the me for me, and liked the "nice" guy. I've had many female friends over the years ask me "Why do I always get the total arseholes? Just one after another?", and I think on this mixed signal "bad boy" theory. All I can say is keep looking, eventually you'll find the right one who'll like you for who you are, not a false front, clothes, cockiness, or what car you drive.