There was one time I had breakfast in McDonalds after being out all night doing outcalls, it was 6:30am and there were 3 of us in McDonalds...
1) there was me
2) a guy who looked like a builder - he had a hi-viz jacket, with jeans and boots on, reading the paper
3) and the third person was a lady who was clearly a working girl - CLEARLY!!! she had stockings on with a very short black skirt and a little black jacket, and had a large handbag, she looked like she hadn't slept all night... we both looked at each other and were probably thinking the same thing - takes one to know one!!