I would say you 2 up in your ivory towers need to get a grip and actually read the feedback. Hardly surprising when you consider what he's selling. People pay peanuts, don't read the description, expect more than was ever for sale and leave crappy feedback.
I've dealt with a number of imbeciles on eBay who left negative feedback for absolutely no reason whatsoever. Sold a SkyMap 2 with a clearly described and pictured mark on the screen, yet buyer screamed blue murder and left negative feedback. Bearing in mind that the majority of the general public are categorical retards I don't think it's at all unreasonable to see odd bits and pieces of negativity on sites like eBay.