I know that for me, being a draq queen (and I would like to think a pretty one :-D) that the younger and thinner girls get tipped first. The sexier the outfit the more money they make. I know one friend who wears little on stage and gets twice as much money as my drag mother does. Not that performing is all about money, but my drag mother isn't really skinny, and I don't think she would look good in pasties and a thong.
For me, I know I wouldn't wear skimpy things either, but it makes me self concious of what people think is worth money and what isn't. It sometimes feels like they tip the sexual skinny friend because she's sexual and skinny, whereas my drag mother tries to make the show more entertaining, more theatre, and people don't really like that it seems (though I do)
weight, really plays an issue in the drag community.