A few years back I took $100 out of one bank and deposited it at another. The second bank only credited me $80, and sent me a letter informing me that one of the bills was counterfeit. I called the bank and explained that while I'm sure they were right, I'd been handed the bill by another bank and I had no chance of detecting the counterfeit bill so it wasn't fair to punish me. They, of course, wouldn't agree with that but they *did* give me a $20 counter credit because they wanted to keep me as a customer.

A couple decades ago when all paper money was as counterfeitable as the $1 bill remains, I worked at a fast food joint and would encounter counterfeit money on a fairly regular basis. The thing is, it was obvious to me that the poor schmo trying to buy a burger hadn't made the bill, and was just handing me a stack of money he'd been handed by somebody else. Who knows where the counterfeiter was? So unless I thought the customer was actually trying to swindle I'd just take the money and let the banks sort it out later.

Similar thing here: the purchasers are unwittingly caught in the crosshairs. Nothing good comes of attacking the person who's already been unknowingly swindled.