...Yahtzee said one thing once that made me extremely relieved to realize I wasn't in fact the only person with a brain in the world:
How do you transform a complex opinion on a 5 or 10, or whatever, point scale?
Anyone else realizes that these values are actually arbitrary?
Unless I'm missing out on something, there is no equation known to man capable of converting a highly complex qualitative variable into a simple quantitative one. I mean, this would make statistics so much easier, but there isn't.
You know how these ratings are done? Reviewer X goes to review game Z. Reviewer X players through game Z and decides first whether or not it made him want to stab his own nuts out with a burning fork. If yes, the final score will be bellow average, if not, above average.
Now Reviewer X mentally picks up another game he already reviewed of the same kind, for instances game V, if he never reviewed one like it, he'll use the best game he knows of the genre, or failing that a utopic vision of such, as a reference and compare it to game Z.
"Was it as good, was it better, was it worst". This is how reviewer X is going to decide what rate this game gets... But how exactly does this work? I mean, maybe it was better, but how much better? Game V got a 9.3, but game Z has much better gameplay, but the story is weaker. What do we add and detract from game V's score? Simple. Introduce a random variable. Something along the lines of: "eerm...Z gets 9.6".
Generally when I see a numeric "rate" attached to a review I rarely bother to read the review. It's a safe sign it's a bad review to begin with.