Sales numbers are not always indicative of a game's quality.

[PS3beats360]

Sales are not a true indication of a game's quality. The review scores are not much of a true indication of game's quality either. The reviews that get posted on metacrtic/gamerankings are nothing more than marketing/hype to push sales of high profiled games.

I have a played a lot of AAA stinker games in my life time - the review system is broken.