Unfortunately, the utopia of objective jounalism would be marred somewhat by total lack of any possibility of 'objectivity' in principle. After all, for popamole crowd Oblivion IS a second coming, especially after a nude mod or two.
We would need some profiles on journos, for instance a list of games they played (and actually completed), their previous scores on those games, etc. Also I suggest going away from numerical markings - because they PRETEND to be objective. They are not. Something like 'an affront to humanity', 'really bad', 'poor', 'meh', 'good', 'exteremely good', 'a shining beacon every other game in the genre should aspire to'.
I would suggest, however, stating a min/average FPS for a range of typical (and reasonable) hardware configurations and game settings - like those in Video card testing reviews.
But, of course, removing obviously corrupting influences would be a start.