As a seller I sold 4 N64 controllers on eBay to three different people. All shipped on the same day. Had positive feedback for three of the controllers, and the buyer of the 4th opened a claim against me saying it was never delivered. I submitted the tracking information showing proof of delivery to eBay and they STILL sided with the buyer, refunding his money. Luckily eBay covered the costs of the refund, but I still think it's ridiculous people try to take advantage of others and game the system.
I've had stuff show delivered that never came. A Rightstuf order in the last year, and a buy.com order 10 years ago. They're not necessarily lying if the tracking says delivered. I've also had one show up days after it said delivered.