I'll ramble on some more, because this is an issue that's compelling to me, both inside the computer industry and across other fields.
There's the story of the movie reviewer who wrote to many negative reviews and was taken off the list for press junkets: loss of prestige, potentially loss of a job. Like in any industry, there's a lot of money at play and it's gotta be tough to balance journalistic integrity and "playing along" especially as one's reputation grows.
The first source of bias is innate: you wouldn't be reviewing something if it wasn't an area of passionate interest, so generally, reviewers are industry cheerleaders. That being said, I think if the reader is equally passionate, they will consult a wide variety of sources and keep a scorecard of who's producing useful balanced information and where.
The problem of course is the huge pressure to be unbalanced. Polemicists are often overly read, if not believed, but readership is a major metric. A manufacturer looking to buy an opinion will look to the ones that are the most widely disseminated. Sadly, more credible sources take a longer time to establish themselves and there's rarely a quick fortune to be made from doing the job the right way.
The good news is that time does heal some of this. There are some fairly well-known and well-read good sources out there, we all have our list of them. The best a reader can hope for is no premeditated inaccuracies and no glossing over glaring problems, and with the constant feedback via review comments and user reviews acting as a powerful bull$&*% detector, hopefully, the basic truth will always come out in the end.
Another favourite anecdote was told an ex-President on Letterman: When asked what he though of another ex-President being paid a million dollars to give a speech in Japan, he said, (paraphrasing, can't find exact quote) "It's not my place to comment on other ex-Presidents, but if somebody wants to give me a million dollars for a speech, I'm there!"
The best reviewers are the best diplomats and can get something across without even having to say it.