I could imagine confronting them quite directly with a fake naive attitude. Imagine they come onto you with one of the typical phrases, you then say,"Ah, you must be one of these Behavior Detection Officers that I read about. So nice to meet you (shake his hand vigorously). Now, tell me about this so called SPOT program. Did you catch any terrorists lately?"

It wouldn't be unfriendly, it wouldn't be illegal, you are not assuming anything or making any judgment. Still, you'd have totally spoiled them on the spot because his "cover" is now blown and they have to use another guy. If someone uses the same technique on the next BDO, they soon run out of BDOs or have to switch them so often that it becomes inefficient.

Till