Have you noticed that the prolific Amazon poster S.Tepper has apparently been banished and all his comments wiped out ('deleted-by-Amazon')? On Amazon.com, whenever it comes to a shill vs a guy with enough civic spirit to complain about it, it's the guy who will lose.
Another telling nuance is that when such a total-wipeout event happens, all posts marked as 'deleted by Amazon' show different dates, usually the date of original posting of the deleted comment — despite the fact that they have all been deleted in one shot on a date that has nothing to do with the original posting date; in fact it can be years later. Obviously this is incorrect, but let's speculate why Amazon would be doing it this way?
Perhaps to create an impression that every post was deleted individually, upon a human inspection, for something being legitimately wrong with it? Maybe the idea was to hide the fact that a lot of such deletions are a gigantic one-blow event, maybe even faceless, triggered automatically, say, by gangs of shills in cahoots clicking with gleeful abandon on the 'report this' button or something similar? Or by one of them operating a bunch of sock-puppet accounts (once more: setting up a voting account is exceptionally easy (amazing that it is so, no?) — all you need is to type a bit of text (any text: gibberish, anything) into a couple of fields on the login page — you won't be able to comment or review (gotta buy something for that), but you will for some reason be given the right to vote).
Unrelately — or rather only somewhat on topic: check out this new post about Amazon reviews system: Amazon: Customers Fight Back Over Fake Amazon Reviews.