I've only had it happen once. I sold a moderately expensive item to someone in Australia (I'm in the US) who wanted it shipped by one of FedEx's more expensive shipping options. I'd sold more than a dozen of these before and a dozen since without a single bad one in the bunch. When it gets there, he says it's bad and says he needs a replacement immediately and suggests cross-shipping them (again, on his account). I ship, he doesn't. Then I find out that if you don't feel like paying charges on your FedEx account, you can just tell them to bill the sender instead. According to FedEx, that's absolutely hunky-dory in their book and as the sender, you are totally responsible and there's nothing you can do except pay. So, I'm out the second item and two high-rate shipping charges to Australia. No surprise that the buyer never responded to any further email after the "replacement" was shipped, and his Ebay account shut off.
I've been a lot less inclined to ship things on buyers' FedEx accounts after this.
