It all started with the work of one of my favorite Amazon Auteurs, Kathy Tontobreine, way back when. Then another one I'm a fan of, JS Mason (he of the "blind architect" shtick) jumped in some time later). Check out their collected works sometime.
Some of these reviews show all the signs of having been written by one person, or a group of likeminded people. There's one bunch of very similar reviews all chalked up to "A Kitchen and Housewares Enthusiast from BROOKLYN."