George,
Believe me when I tell you that your preaching to the choir. Being PC wasn't what I had in mind. You will recall that I'm one of those that will call a spade a spade in a heart beat. It wasn't to long ago that a flame war permeated this news group over just such. It changed very little, drove a lot of people away and created a lot of anamosity.
Trying to confront an asshole usually brings out the asshole in one's self. Stepping forward and telling someone they are acting like an asshole usually doesn't change that individuals out look. Most of the time, it does have an effect on others, though. It's kinda like the village idiot. Everyone thinks they know who it is, but really no one knows who it is until you join in and open your mouth, then everyone knows that it's you.
So, how about this? "Item is as described, what part of 100% refund did you not understand? Leave it at that and move on. No sense in getting on your ear over some little neutral feedback that has no effect on your ability to continue selling. Terminate the guy in other ways. Challenge him to a duel of honor, pistols, or swords. Kill file him and block him from bidding on your future listings. Black list him by telling others who he is, provide facts, and let them do the same. Heck, if you really feel he deserves it, send him some black roses, seeded with maggots. Send him a black card containing a smelly pair of ole brown streaked boxers every year on the anniversary of the dirty deed.
Keep this up until one of you blinks. Either he has a heart attack, or you do. I suppose you could say you made your point, if he blinks, first, and dies! Of course, if you blink first, then what are we to think?