Today eBay reversed a payment I received for selling a phone. I had sent the phone on the way to the airport and kept the receipt in my backpack in case I needed to verify that I sent it. A couple weeks later I saw the receipt, figured everything was done, and threw it away.
And then this guy files a claim that he didn't get the phone. I write him back asking for more information and giving him the dates and times I shipped. He doesn't respond. Ten days later I write him again to make sure he got the phone and everything was okay. No response.
Paypal had taken the money out of my account, making it negative, but after a while they reversed the money back into my account. Seemed like everything worked out.
And then this morning I wake up to see that the seller, without contacting me, escalated to eBay and eBay sided with them. So the guy got a free Nexus 5 on me.