There is a certain level of hypocrisy with how games are reviewed ...
For some reasons a reviewer will look at Halo 3 and ignore its weak single player gameplay and give it an excellent score because of how great its multiplayer gameplay is; at the same time, this type of focus is denied for games like Mario Kart, Mario Party and other heavily multiplayer focused games. At the same time a reviewer will look at Bioshock and see its lack of multiplayer gameplay as a strength while docking marks from Metroid Prime 3 for lacking a multiplayer element.
I'm not saying that these games should receive similar scores, but the criteria for how a game gets the score it receives should be fair and predictable; these reviewers shouldn't constantly change the review criteria to justify higher scores for some games or to justify lower scores for other games.