However, I wouldn't label you a scammer if you didn't sell me my shrimp. If it sounds too good to be true, it probably is.
If I never intended to sell you the shrimp but repeatedly promised that I would sell you the shrimp and wouldn't weasel out of it and you contracted out a buffet, hired chefs and servers, and then I ddn't show up with the shrimp and said "Ha ha, sucker! What a great prank!" -- I'm pretty sure you would.