The main problem I had with one that I worked with was how it was jampacked full of teenagers. Try getting them to pay for anything. It was a non-adult site - just pic rating, profiles, forums. Became a very popular site, though, with over 1.5 million members at last count and one of the best known rating sites out there. So even with a small percentage of folk being paid members, it's still a big enough number to generate quite a lot of revenue. And ad revenue made up a significant portion of income too. Could charge a hefty amount for ads when you have 1.5million users.

It was entirely non-adult, though, so I can't really speak to a couple of the specifics you mentioned, Jay.

All in all, though, I think they do quite well. People like the voyeurism/exhibitionism aspect of them. They like to show off and like to see real people. Give them the opportunity to do that and they'll most likely take it.