When I was a cop, a bizillion years ago; I walked a beat in a market district.
I was always on the watch out for thieves. What always caught my eye were people who were paying more attention to those around them than to the merchandise in front of them.
One day I'm walking my beat and a fruit seller I knew engaged me in conversation. She pointed out a person and said "Is that at 'cd'?". Up till that point I had not given that person a second glance. She wasn't too tall, she was dressed nicely; but business nicely, not going out dancing nicely ( It was 10am). She calm cool and collected. Honestly to this day, I'm not too sure if she was a CD or a GG with a somewhat manly facial structure. It was her total and complete air of "I'm a normal person doing a normal activity"; that really made me second and third guess myself.
Hard to do on the first try, but the take away from it is to not react when people look or say something, just move on and ignore them.
