Just out of curiosity, what would happen if the farmer claimed that the bills were counterfeit? If that claim were true, no money would have been destroyed and the offer to purchase would have been fraudulent.
Sadly, I don’t think that after the bills went through the goat, they’d be in good enough shape to sell the beast as a money-pooper, what with goats being ruminants and all. (Everything gets chewed again after it’s softened for a bit.) That was a really cool idea.
And does ipecac work on a goat? If it does, the goat could be persuaded to give the money back, right there in the pen.
To be fraud, the seller would have to prove that the buyer misrepresented a material fact or made a false promise at the time of the contract. Just claiming counterfeit bills alone wouldn’t be fraud because the seller would have no proof that the buyer knew the bills were counterfeit at the time or that the buyer never intended to perform. The only thing passing counterfeit bills proves is that someone passed counterfeit bills; it says nothing about intent.