I agree wholeheartedly. Yes it does sound silly, and yes it may be the very last thing that anyone would suspect. It also may be highly effective for them.
My family visited the Fort underneath the Golden Gate Bridge on Saturday. My husband witnessed a large group, approx. 30, Muslim men in the parking lot when he went to retrieve the car. He said they were milling around our vehicle, and they were looking "furtively" around. He saw no cameras, but he said they were sure behaving suspiciously.