I am still really really confused as to WHY buyers care if they get a retaliatory negative?? Unless your FB percentage is truly horrendous, no seller is going to cancel your bid on their item for having a negative that they can clearly see is in response to a neg left for a shoddy seller.
This is my main complaint with eBay's feedback system: the people who should be leaving negatives don't and then other unsuspecting buyers end up with negative experiences from that same seller because no one bothered to warn them via feedback.
The thing is, in my case at least, if I had left a neutral for every transaction that I wasn't completely happy with (before I became slightly more eBay-savvy and started asking a lot of questions before bidding), I would have left one for at least half of them, one way, or another and at least 1 in 5 of them would have got a neg!
I think that's partly why it doesn't happen more. You soon realise that experiences on eBay are all relative - a totally positive experience is rare (until one is wiser) and a neutral, or slightly negative, experience is, frankly, the norm.
There is also the old chestnut of 'eBay etiquette', which some sellers accuse newbies of not understanding when they leave a neutral, for what the seller considers to be, a relatively minor problem; like poor packaging etc.
I was thinking of starting a 'Campaign for Honest Feedback' on here, to try to promote the idea that a neutral experience should actually receive a neutral and a negative one a neg! As opposed to the current 'etiquette' where a positive is given for anything better than a really bad experience and a neg is reserved for near-criminal, or criminal, behaviour! Wouldn't that be refreshing?!