Buying and Selling of feedback

[I know the following doesn't respond to the exact question asked, but it's tangentially germane...]

The feedback system as presently implemented, both here and on ebay, is too intrinsically susceptible to pressure and manipulation to be of much use. Negatives will always be underreported, due both to a justified fear of retaliation (I know, it happened to me on ebay) and to the prevailing informal quid pro quo concerning the trading of generic positives.

I have fantasized about a possible technological fix (not that I would have the faintest idea as to whether, or how, it could be practically implemented): It seems to me that if a feedback system could be designed so that neither party (and maybe no one else either) could see one of the feedbacks before the other was posted (in other words, neither party would have to 'go first'), then each feedback could be written more honestly without fear of reprisal. This would also be a somewhat 'followup-proof' system, in that one party would look pretty foolish if they initially posted positive feedback when they were unaware of the other party's complaint, and then went back and followed-up with secondary negative feedback in obvious retaliation. The inconsistency would hang them by their own petard.

As an analogy, think about a properly functioning electoral democracy: You must implement the all-important secret ballot for it to work as intended. My 'double-blind' feedback system idea is the equivalent of the secret ballot. Like I say, I don't really know how or if this could be accomplished, but to me it doesn't seem very far-fetched in concept. Any opinions?

Good addendum, SW - this sort of provision had occurred to me when pondering the idea before, but I forgot to include something about it my post. Anyone perusing a member's feedback, who cared to crosscheck the feedback that member had left for others, would be able to infer from its absence that the member was not timely in posting theirs, or just didn't care. And a member posting negative feedback honestly would remain protected from arbitrary tit-for-tat reciprocation, since any lack of corresponding feedback would imply that the non-posting member had nothing critical to report (otherwise we could assume they would have felt motivated enough to do so), and that could be taken as a 'virtual positive'. I think 30 days from the submission of the initial feedback ought to be a more than sufficient 'quarantine' period.