If it's been said once, it's been said a thousand times: the best advertising is word-of-mouth. What's meant by this is that a person is more likely to try a product or service if someone they know has recommended it to them. The reverse is also true: if a friend or family member recommends against something, the referee is similarly likely to avoid it. What makes this phenomenon work is trust. People trust the opinions of those close to them, because they've spent enough time with them to understand in which ways their tastes might overlap their own.
But does this still work with game reviews, when the only way you've come to know the reviewer is through reading their reviews? Can a trust relationship evolve from what is, essentially, one-way communication? Is a commercially-funded review source more or less trustworthy than a writer's personal blog? Can numerical scores relate actual value?