Posted By:
Jeff Prillamanthe 90 days doesn't work -- you can leave a negative a year after the fact as long as you have the item number - unless ebay has changed that loophole.
But the best suggestion I have seen (and I use) is to have a buying and a selling account. For the most part I could care less what percentage a buyer has -- i just want to get paid - but your reputation as a seller needs to be protected. Hence you can leave "well-deserved" negs and not really fear retailation when you have separate accounts. The only time I use a buyer's feedback is when there is an issue it enables you to see the characteristics of who you are dealing with.
The other advice is don't bother with a neutral -- especially when 9 times out of 10 it invites a negative -- go ahead and neg right from the start.