As sad as it may sound, I know some... let's call them pathetic individuals... who pay 0.01$ exactly because of this fact. But oh well, they are usually pretty laughable with their feeble attempts at trolling, anyways, so I stopped bothering quite some time ago.

Surely they wouldn't put the transaction through unless they were getting money from it though?

That's a good point! If they're not going to make any money, there's no sense in even taking it. Though, it might be illegal to sell something and then not accept payment. (Fraud? Money laundering? I don't know, but it seems potentially sketchy.)

It's not fraud or money laundering. You don't see people refusing payment for the simple reason that most people would never give their stuff away for free.

I didn't mean to say that it is fraud or money laundering, just that it might look like it.

Anyway, what's the difference between giving something away for free, and selling something and receiving $0?

I recall hearing that's the reason Proun requires at least a $2 payment