In 1978, while visiting in Nahant, MA, I heard a story from a friend and successful businessman about a shipload of tuna sitting in a North Sea harbor waiting to be unloaded. The owner of the cargo received a phone call telling him that the ship was being denied access to the port by government authorities. He desperately needed a way to unload the tuna anyway he could. He promptly located a buyer to take it off of his hands by selling the tuna before it rotted at a fraction of its retail price to minimize his losses. "I have a great deal for you, Bill. You can buy this tuna that is sitting in the harbor and resell it at a profit. You can make a fortune." Bill bought it and saved the owner from total ruin on the shipment.
Bill called on a friend of his to be a buyer for his tuna. Bill said to the buyer, "I have a great deal for you. You buy this tuna from me. I'll make a profit. You sell it and you can make a profit, too. The price to you is still way below the market price."
So John bought the tuna, making a profit for Bill. John knew a man who owned a supermarket chain and offered the tuna to him at a profit. Kevin bought the bill of lading and arranged to have the ship eventually unload. After a few days of dealing, the ship was unloaded and the tuna was distributed and stocked in the stores.
It was only a few days later that the reports started to come in. People were being made ill by the tuna. Kevin called John to complain. John made a hasty call to Bill and Bill called the original owner. He was more than a little bit perturbed. The original owner blew his stack, "Hey, it's not my fault. I thought you understood that the tuna was not for eating - it was for buying and selling."