Ebay really needs to clarify the word "feedback" Is this just a comment, an opinion, response or criticism?
If you can only leave "positive" feedback for a buyer (who may in fact have kept you waiting the maximum length of time for payment, before you could list an unpaid item) then why bother to have this facility at all?
By the very nature of the ‘lack of choice’, the whole process is superfluous. Better to scrap the feedback system altogether then we are back to a level playing field and buyer and seller beware!
As it stands, buyers can bid/buy with no intension of paying, knowing that they can carry on doing this as long as they like, and the buyers have no recourse other than to claim their fees back at a later date, but no one pays for the time wasted!