While I agree, it is a slippery slope no? If you swiped your card, you did at some point agree to pay that amount for the art, no? To say it later becomes fraud because you were told it was done by the "art student" seems a bit slippery to me.

In the end, just avoid these situations all together, but I think if you buy and pay for it keep it. Don't get mad later just because you got ripped off by a fake art student.