I don't use any of these sites and am always amazed at how much information people put on them, especially that which they use elsewhere too.
A while ago a girl appeared on Adultwork in my town using a distinctive nick which I Googled out of curiosity because I liked it, and wondered if it was a film character or something. In less than a minute I had her MySpace page with her full legal name and that of her sister, pictures of her and her family and shortly afterwards thanks to 192.com I had hers and her mum's home address - I emailed her to warn her and she was horrified and had no idea (she vanished within 24 hours and never reappeared, and I don't think she really understood what the site was). If I could do it, anybody could - punter, neighbour, workmate or whatever, and I can't imagine she's the only one to ever do it.