Considering the average a 40 is harsh but if it's on a 5 star perhaps 60 wouldn't meet his feeling on the game and he misses 50-55 option of grade...
Also some people may have really loved it so a 90 may be genuine...
Judgeing from what Ive seen, I dont think theres any defense for a 90 score.
Reviewer must owe MS a favor or something :P
Necro-bump this 2020: http://gamrconnect.vgchartz.com/thread.php?id=229249
Bumb in 2021: http://gamrconnect.vgchartz.com/post.php?id=9047071