There are no questions you can ask prior to a meeting. Don't be fooled by anyone talking about an "LE check" there is no such thing.  Nothing either of you says, grabs or exposes guarantees that you are not in the room with a cop.  Cops lie. Regardless of what others may say or post this is a fact.

The bottom line is, if you are already in the room with a cop you are already screwed, and not in a good way. Plan on getting arrested, going downtown, getting booked for soliciting.

How do you avoid this?  The best way is to stick with established providers who are reviewed here on TER. Nothing is one hundred percent foolproof but sticking with discreet ladies who have a history and making sure that you don't do anything on your end to attract unwanted attention is a good way to insure relative safety.  There are a lot of risks in the hobby and very few guarantees. We all have to decide how much risk we are willing to take and act responsibly to stay as safe as possible.

We dont
until we research/screen thoroughly..

... this can go for either...

If he or she is on phone when answering door, why would you be on the phone when you are meeting someone?  Know what I mean?  Obviously, they'd want to be discreet.