When Yahtzee says a game is good, I immediately give serious consideration to picking it up, I generally consider him a decent authority on "good" titles.
When he says a game is bad, I ignore him and read other reviews or rent the game first. He plays far too much for comedy when he says a game is bad, but then again, this IS WHAT HE DOES, I know to expect it, and I always take his game shreddings with a grain of salt and just enjoy them for the comedy.
That's pretty much what you SHOULD do with any critic, learn their quirks and biases, and then you can gain more useful knowledge from their reviews.