I experienced a screening technique that a few of my providers have used on me and I thought may be some the providers on this board might find it useful. When I went see a provider, she asked what color and make of my car was and asked me to park in a certain place where she could see my car from her room. After she saw my car she gave me her room number. When I went to her room and knocked, to my surprised she opened the door from the room opposite to the one I knocked! Luckily there was no one in the room otherwise I might have been in trouble!. When I went inside her room she told me this is how she screens her clients. I do not know if there is any way for anyone to tell from color, make of the car or by just looking at person from a peephole if he is not LE but I found this method interesting.