I'm really surprised by the Gap return. You can't return ANY worn merchandise there (unless it's defective)and, typically, that policy is strictly enforced. I know this because, until recently, I was in the Customer Relations department there and I had to talk to many, many, many angry customers who had their returns refused.
I have to believe that the person posing as the customer somehow communicated to the cashier that the items hadn't been worn. We didn't see much of the interactions between the customers and the store employees. Something just doesn't seem right with it.
That said, I'm also pretty positive that it's against company policy to resell anything that had been worn (which is typically only defective stuff anyway).