Great stories!! I don't have anything that matches the stories here, but my favourite trick that a couple of people tried to pull on me was agreeing on a price and when we meet, they show up with not enough cash and say that's all they could come up with. No matter how desperate you are to sell, play hardball. I would ask why he didn't mention that earlier before meeting up. Usually I just tune out whatever he says in response. I be nice and say "I wont go lower than the price on this grill, but if I'm selling a cheaper entry-level grill in the future i'll email you". In 2 out of 2 situations, he finds a few bucks in his pocket that he forgot about. The best part about both situations, they came to meet me about half a block away from my house - morons spent the time to travel across the city to meet me, not much of an inconvenience on my end.
And to look at the other side of the spectrum. I purchased a cheap weber kettle last fall and when I saw it in person, it was a bit dirty. To be honest, I had no problem with that - I was going to give it a deep clean regardless. But the seller (she was the kindest person I have ever dealt with on CL/other sites) almost forced me to take brand new unopened cleaning products, with a value equal or higher to what I actually paid for the grill, despite me saying that it was not necessary at all. But the morons out there who clearly watch too much Pawn Stars are much more entertaining!