I just would like to offer a viewpoint that was told to me from someone I know to be a credible source. My next door neighbor owns and operates a very high end AV sales and installation company here in the New York area. They do whole house installs (audio, HT, security, smart-house controls, etc) that are often well into the mega 6 - low 7 figures, often on homes/estates that cost or are worth double digit millions, and often owned by celebrities, top-of-the-line doctors, lawyers, business owners, banking execs, etc.. Years ago, he worked in sales in a very high end audio boutique shop here in Westchester County, and I say all to establish that his experience and knowledge is quite extensive. He personally knows or knew many sales reps from the high end companies, as well as most of the editors, publishers, and reviewers for the US audio magazines, and again, I am just saying this to establish that he is not simply talking from hearsay or innuendo.
I once asked him this same question about why the mags all seem to only rave about the products in their reviews. He told me that very often, companies and reviewers have an under-the-table arrangement set up, whereby the company ships a piece of equipment to the reviewer, then "accidentally" forgets to ask for it back. The reviewer then lists and sells the piece on ebay or audiogon under an obviously disguised alter identity, and the companies can then honestly say that they are not "paying" for a positive review, but instead, the writer who is making peanuts from the magazine for his reviews receives this "bonus", and this supplements his income. He named many recognizable names in the high end audio field that we all have heard of, which I will not repeat here, and says that reading these reviews simply equates to reading ad copy.
Now, I am sure that there must be exceptions to this practice, but he feels that it is very prevalent, and an ugly little unspoken secret of the audio and HT field that he knows of firsthand.
I personally tremendously benefit from reading forum members' personal reviews on this and other audio websites, as the technical background and audio experience of many posters equals or often exceeds that of these pro reviewers from the mags.