I recall reading stuff written by security experts about some tale-tale signs that they use to pick out the BG's. It seems one of the biggest ones was what they called "swivel-neck."
The problem with looking out for the 'swivel necked BG's' is not looking like a 'swivel necker' yourself.
Nah. Not that hard, really. And so what if you do look like one? Staying aware of your surroundings and potential threats is hardly paranoia.
We must always remember that the founder of 'Game theory', John Forbes Nash, the mathematician whose ideas were so beloved of the RAND Corporation was himself a paranoid schizophrenic.
So what if he was? And he is not the founder, as far as I know. That distinction should probably be given to John von Neumann and Oskar Morgenstern, though Nash was surely a major contributor to it.