I'm appalled that anyone can think that buying a favorable review is acceptable for a self-pubber.
The practice of paid reviews is just one more strike against these self-professed authors. Who needs to hone the art and craft of writing, who needs to pay for competent editing and cover art--the hell with all that, just buy a glowing review! And then pretend it's the normal course of business and accuse the traditional publishers of doing the same thing, because ... well, there's no evidence that they do, but we all know how evil they are.
A review is not a blurb and it's silly and disingenuous to lump them together. Of course traditional publishers cross-promote their authors with blurbs. So what?
How many of you who are defending Locke have been adamant about the evils of piracy, and have accused the pirates of stealing the food right out of your mouths with their shenanigans? Is it all right, on the other hand, for the author to defraud the reader--to take the money from his pocket--by hiring a shill to lie about a shoddy, inferior product?