Don't worry DW, when you see one the hair on your neck will bristle, the adrenalin will pump and your sense will become sharpened. Self preservation will kick in and all qill be right with the world.
By the way, how do you know a criminal when you see one?
Excuse me a minute, I have to report you.
That's just it, I don't know one when I see one, so, that leaves the question, how does a person report one ?? Also, about the hair standing up etc when you see a terrorist, why didn't that happen to all the passengers traveling with that shoe bomber, the flight school owners and the list goes on.