Crosmando: No, just common sense. I take a look at a screenshot or two, a gameplay video (minus the annoying commentary of someone dubbed over it), and I even read the description of what the game is about, and what type of game it is. If it takes my fancy, I buy it, or if a demo is available I play that.
And then (shock horror) I play the game, and then make a decision, with my own brain, of what I think of it.
except that by then it's already too late for your opinion of the game to matter. the point is to form an opinion BEFORE committing to a purchase, in order to avoid buying games you'll end up not liking.
Crosmando: I cannot fathom how a person could could value themselves so little that they take the opinions of others in something like video games.
you're completely missing the point. you read reviews in order to figure out if a given game might be something you'd like, how it fares compared to similar games you might already know or have, how well it has been done, how much content it has, etc.
you can discard a reviewer's opinion of the game if you don't agree with it, but how else, if not by reading reviews, would you learn about the aforementioned points BEFORE buying the game yourself - and potentially wasting money?
and that's not even taking into account a critical analysis of a game. but then again, these are so rare that it probably wouldn't play a role in your decision to read reviews or not.