Although I always love reading the next big take on the hot-crazy line, I actually think that the big difference between gorgeous and ugly people is how much effort they put into their appearance. At least for women, a lot of us could look a lot prettier if we put in more effort.
I suspect SOME of this hot-crazy thing is that when we do put in effort and wear makeup, heels, and nice clothes, we get hit on a hundred ways to hell and have to use a sour attitude to deter creeps and assaulters. If we surround ourselves with ill-fitting clothes and never cover our acne scars, we're protected that way. When I look good AND smile at a guy, he might assume we're getting married. (This is only half a joke. Guy friends are notoriously bad at taking "no" for an answer and a lot of men think "no" is itself bitchy.)
For straight women, I've heard they just don't care about attractiveness in men as much as men do in women. So to all the women responding, I think the market is just very different for us.