I really don't like when reviewers give certain games passes just because they belong to a certain franchise or because it was heavily hyped before release. It's like they don't want to disappoint the fans or something, so they give the game a higher score than it really deserves.
Also, and this goes hand in hand, when reviewers overlook a games shortcomings just because it has high production values, or a moving story and/or cinematics, even if the gameplay is lackluster.
Like those things are nice, don't get me wrong, but this is a GAME first and foremost, and if the gameplay is mediocre, it really shouldn't be getting perfect scores across the board, imo.