Big pimpin'

You may have read recently about physics professor (Farleigh Dickinson University, NJ) David Flory's arrest in connection with a web site promoting prostitution.

What I don't understand is how sites like Seeking Arrangement (previous posts here and here) avoid this kind of attention from law enforcement. The fact that the arrangements are negotiated privately between users of the site may insulate SA, but surely the police could nab plenty of Sugar Babies and Sugar Daddies in a sting operation.