I have two different attitudes about women's attractiveness, based on the situation. When looking for a date or a girlfriend, I tend to go for the plain-looking ones. They don't have as many men interested in them, which would mean less competition for me (and higher odds of her liking me). At the same time, plain-looking people tend to have better personalities, since the society doesn't just hand them everything on a silver platter, so those people end up having to work for the things they get. And working for something usually builds character, and makes you appreciate what you get. In the end, she's happy because she found a good guy, and I'm happy because I found a girl who appreciates me. I don't see it as "preying" on women with low self-esteem, since I treat the women I date very well, and don't expect anything they're not comfortable doing.
When choosing an escort (who I'll only be with for an hour or so), my attitude is a complete 180 of what I described above. I pick out the best-looking one, with the best body. I also check the reviews to make sure she has a friendly personality as well, but that's secondary. As long as she looks hot, and puts up a good act of liking me, I'm happy. Most escorts I saw fit this description.