I've blocked him for ages. Not sure why more didn't do that. But if any buyer asks me to cancel a sale, I will do it and then immediately block him. Frankly, I wouldn't force a customer like that to remain in a transaction with me, I wouldn't want anything to do with him. He can leave bad feedback, file fraudulent claims, cause all sorts of crappy problems. Remember, this is eBay where the buyer is king, and all the scammers know this. eBay members are either scrupulous or unscrupulous and their behavior generally crosses both sides of the selling/buying aisle. I have never had one legitimate negative FB. Any neg I ever received were all scam FBs. The latest one is where I made a purchase of a DVD. I asked him questions about the item before I made a purchase (will it play in USA since it was supposed to be from overseas). He said yes and I purchased it. It was the lowest priced one. Maybe he changed his mind, then decided to cancel my order without any communication to me, I suppose he wanted to sell it for more now. If he had contacted me and let me know he couldn't fulfill the order, and he could make up any excuse, and I would've been OK. This had happened far too many times already and I always let things slide. Every time I purchase an item for cheaper than the seller wanted, they always cancel and refuse to ship. Anyhow, I left him negative feedback and he flew off the handle. Said he broke the item, left me tons of messages. I ignored him. Suddenly, he immediately turned around and purchased one of my items (a vial of touch up paint). At that point, referencing the touch up paint sale, he immediately continued on about the DVD and FB. Sensing that this was an attempt at extortion to correct FB, I contacted eBay and told them the story because I didn't want to ship his paint nor want any business with him. They recommended that I ship it because the buyer paid and could leave me neg for not shipping (like he did). So I went ahead and shipped. When he figured I wasn't going to edit the FB, he then left me a neg on the paint transaction, even though the whole PM trail only was about the DVD, an entirely different transaction. He left neg before the item even got to him, the FB said rude and all sorts of nasty stuff. Well, I contacted eBay and they removed his comments but the neg hit remained. I called again, they told me it might take a few days to disappear. It never did and I gave up. It's been slowly diluted, and now is only a hint of what it was. The bottom line is that bad customers can cause all sorts of problems which if nothing else, wastes tons of your valuable time. So if a customer gives me any hint of being a future problem, I'd gladly drop and block him like a hot potato.