Of the three you list I had to have another provider vouch for me to the owners of the sites. They also looked up my ad/posting history, website and reviews.

You can only read back through so many dozens of pages before things start to blur, so..

There are plenty of threads talking about client verification sites such as P411, RS2K and Date-check. Clients give their information: name, addresse, employment, home and work numbers.. What kind of info does a provider give to these sites to prove they are actually a provider? Especially when some sites let providers create there profile for free and only charge the clients.  Do they have to have references from established providers that can vouch for them?

I kind of figured there it would be something like that but wasn't sure. Thanks for the replies!

This doesn't answer your Q but it might address your concerns: Even if you do find someone you want to meet on another site, CHECK THEIR TER REVIEWS, too.