MERB reviews work like any other community reputation engine
If we were reading reviews of the Helen Rochester of Whores, there would be a single review, by a connoisseur, an expert in the field.
That paradigm seems to have been replaced these days by community reputational engines. See, for instance eBay, with seller and buyer ratings, so you know who you can trust.
Or
Yelp.com - a single review isn't likely to be very helpful, but if a critical mass of people rate something highly, or poorly, it is likely to be great, or bad as the case may be.
A shill post may cause a brief run on a given girl, but if she can't fuck worth a damn, or isn't as hot as the review claims, that will be played out in due course, on the board, with contradictory information. In essence, an overly enthusiastic review can only serve to hurt a girl's business in the long run.
As to the moderators posting reviews; I did ask this question some time ago, and don't recall seeing an answer. 'do moderators suspend doing reviews during their tenure as a Mod on this board'?
Not that I see anything wrong with a Mod posting a review; or even the dread 'shill review' in a community forum, the edge cases of reviews that run contrary to everyone else' experience can easily be spotted, and discounted.
A friend of mine has done some paid work posting shill reviews of some agency girls to this and other boards. The agency gave up on doing it, they found it easier to just hire hot girls who know how to fuck, and let real reviews, from long-time members do the advertising for them. It provided, bottom line, better ROI.