Rules of thumb and experience
I've never had a provider ask what I wanted before I got there. Closest was one who asked which section of BP I found her ad in (she was in esc, BR and massage. I went with massage. Come to think of it, she was one of the best). Google the number, Google the pics. If no hits, be very careful. I think all BP providers I've seen are by the hour not by the service, or at least service isn't discussed until she's passed a clear LEO check. Harder to get capped when you're just talking about how much time you're going to spend together. It is 100% legal to charge to be arm candy for an exec and end the night with a peck on the cheek or sit in their room and chat. I can't think of a time I've ever been worried on my way to an incall or waiting for an outcall. Just the normal elevated spidey sense for words of entrapment, which would be before the fee changes hands.