Bloody hell. When I was in the fruit and veg game, a compatriot in the field let it be known that he always had a Monday 'damaged bin' where he sold off at a discount the weekend's damaged or 'distressed' stock.
There was a post, not sure if it was here, about someone who worked in a box DIY store at the paint counter. They noticed that one customer would order custom mix colors and then always say the color was wrong and not buy it. When that happens they put the unsold mix on a discount shelf. This employee realized that this customer would come back a few hours later and buy his custom mixed paint, that was supposedly unacceptable, off the discount shelf.
Once they realized what the customer was doing, the next time the customer got a 5 gallon mix and said it was not acceptable the employee kept the can behind the counter instead of immediately placing it on the shelf. The customer came back a few hours later and, after searching the discount shelf, asked the employee what had happened to the 5 gallon can. The employee, with his foot resting on the can behind the counter, replied, "Don't know. Someone must have bought it."
They did sell the can to a nice couple later on and after a few more attempts I believe the scammer realized they were on to him and stopped doing it (i.e. went on to a new store with his "trick").
A store I worked in had a strict "no discount for damaged merchandise" policy because of people deliberately damaging items hoping for a discount.