negative feedback IMO, is for when the seller is unwilling to resolve it outside of paypal, and has basically shafted you.

I sold a set of clocks for a motorcycle once, and this particular model of bike the clocks and the adjuster for the clutch cable used to rub. It was just one of those things. I took a picture and posted up these clocks, sold as seen noted in the description. This guy gets them and complains, we agree to refund him and he leaves negative feedback. After that, we said he could keep them.

Personally, if a situation is resolved ambicably, that's positive. If you're left dead in the water, negative.