> If post sale it turns out the money was fraudulent, does the artist need to pay it back?
Maybe? IIRC, if you unknowingly buy stolen property, and they trace it to you, I think you have to surrender it to its rightful owner (without compensation from the police).
I don't think that works with money, though. I can't imagine someone who sold a house to Bernie Madoff would have to give up the proceeds of the sale years later when he is found out to have been running a Ponzi scheme.
Maybe? IIRC, if you unknowingly buy stolen property, and they trace it to you, I think you have to surrender it to its rightful owner (without compensation from the police).