I do believe as well that people who own servers shouldn't be running around reviewing other servers; it's quite possible that other server owners will be biased towards other servers because subconsciously they compare that server to their own / want their server to look better than the one being reviewed. Server owners should also be more concerned with their servers and not running around playing on others'. I'm a mere GM and I wouldn't run around reviewing other servers, good or bad.
At the same time, when I see sometimes they review a server quite well, I ask myself if it really matters, but I do believe a hint of biasement still rests. Only server players should review servers.