The Choicepoint of Johns

Of course, it makes complete sense. From the Freakonomics blog, an interview with an "escort":

Q. Do you typically know the true identity of your clients, and if so, how?

A. Yes. Always. I insist that they give me their full names and their place of work so that I can contact them there before we meet. I also check their identification when we meet. I also use verification companies, which assist escorts in verification of clients. These companies do the verification of the client and put them in a database so that when the client wants to meet with a girl for the first time, he doesn’t have to go through the verification process again. For a fee, I can call in and they will tell me if the client has a history of giving the girls problems, where he works, and his full name.

Of course, there are legal escort services, so the verification companies are legal too. I just wonder: are they online services? Telephone only? Subscription-based? Per-inquiry? Do security breaches need to be disclosed?