I'm convinced there are people who just get no better satisfaction from life than giving others negative feedback. I think that would be stating the obvious, but it's so TRUE on ebay.
Rather than try to work it out with the seller, they'd rather just bad mouth them.
I've never sold anything on ebay. So I'm not saying this from experience, but I just did a transaction with a seller who had some negative feedback and the transaction was my BEST EVER. Fast, accurate and friendly...and this on a $9 item. So how they ever got negative feedback is hard to say. It's sad (but kinda fun) to read the negative feedbacks. Usually it can be easily determined that posters are not TOO intelligent. I'm sure they are also looking for someone to blame everything on.
I've only had one experience on ebay that was so-so. A laptop battery....
They replaced it for me a couple of times, but I should have just tried for a refund.
It was a new battery, but was a piece of junk (the charging circuitry in it). They all behaved the same...OK if you didn't let them get too dead, but would NOT charge if they went too low.
I put the cells from the NEW pack in my old battery and that was the resolution.
Some of the Chinese knockoff laptop batteries are just not well made.
Some are OK. Depends on how complicated the guts are, I suppose.