I pretty much only read reviews for video games and RPGs. Can't stand the movie theatre, so I'll just watch the movie for free when it hits Netflix. If it's a bad one, meh - nothing but an hour or two lost, but a lot of the times, reviewers have nowhere near my tastes for movies.
As for Video Games, I don't care much about the particular reviewer - I look for keywords that are somewhat universal and compare them to multiple reviewers to see how many times those keywords appear, for a sort of consensus. I don't play 'visual novels' or other 'slow-moving' games (though my wife does, so I keep an eye out on those for her), so that's one of the first keywords I look for. Additionally, I look for mechanics references - "This game plays a lot like GameX." Well, I didn't like game X. That reference has come up a bunch of times, no point in wasting money on this game. It's very scientific in that it's not, but it is functional to my wallet and my tastes. Never been wrong about this (cause eventually I'll get a game 3 or 4 years later when it's like 3 bucks on Steam just to prove I was right).
And then, there's RPGs. How to quantify what I look for in an RPG review?
I want it all!
I want some analytical information (the mechanic is d20 + numbers vs. target), or, if dealing with a campaign, I want someone's expectations of time spent reading through it, preparing the material, and how long they expect players to take in -their- group. I don't like generalized guesses like some people write on their adventures - that is never accurate for my home group (they're long-winded, go off trail a lot, and tend to take their time with every detail that interests them). So I would have the reviewer write their group's general approach to games, and thus the expectation for 'that type' of group.
I want some bias information - their opinions of the art (without silly labels and classifications), the writing (again without labels or classifications), the layout, and perhaps the durability. They are opinions, and this department isn't going to sell me on a book or send me away from it, I just like seeing it. It adds spirit and voice to the review, so the reviewer becomes human and it doesn't feel like a machine with the previously mentioned analytical information.
I want some experience, or anecdotes. "This adventure reminds me of when my first DM took me to [insert something relative here]." Again, this won't sell me on the book, or shove me away, but it adds an element that I can appreciate from a human being writing something that is already going to take a while to read, if done correctly.
I want their information in the hobby; how long they've played, the types of games they play the most, and anything else that could help me get a clear understanding of how they approach gaming, and thus whether or not my players and I will relate to it. I'm a bit of a grognard; started playing during the original release of AD&D 2E, and I remember the DM vs. Player mentality that comes from that era. Knowing whether someone has overcome this, or still adheres to it, is very important for me to respect their opinion.
So what is it that tells me not to buy an RPG product I'm considering buying? I just avoid the consensus keywords clunky, gimmicky, all over the place, and a few others my brain isn't wanting to put forth to writing this sickly morning.