Finally -- and this one is extreme, but possibly quite amusing -- a call to the Department of Homeland Security, once again, well-thought out and carefully measured in tone, which alleges that during your call with this "belligerant fellow who refused to give his name but who claimed to have a PHd -- in chemistry or microbiology or something", in which he made a vague but sinister allusion to "only wanting to deal in large amounts of fermentation supplies -- some of which contain high quantities of nitrogen compounds". You let them fill in the blanks, and maybe add something about an off-hand anti-tax or anti-government comment he made "if memory serves". End up by stating that it was nothing overt, just a vague feeling of unease that you got when dealing with him. If even a minimal and informal investigation is started, the bad rep for customer service and relations might seem like they really don't care about doing business -- which could, in turn, make an agent wonder what they're REALLY doing...?
-David