As a buyer I sometimes make a conscious decision not to leave feedback when a transaction has not been quite 100%.

I may have been slightly disappointed in some aspect ...but not enough to leave a neg or a neutral so I dont leave any feedback at all.

I would not like to think that eBay would then fill in feedback on my behalf and score it positively . If this were to happen it would make me rethink ...sellers that I do not score now may get neutrals ........