XBLA Fix addendum

Microsoft has an advantage that other sites such as Amazon, etc. don't. Ownership verification.
You can prevent people who haven't even downloaded the demo from writing reviews or ranking a game. At least this would be possible if Microsoft fixed their DRM for Live games.

Microsoft could prevent a LOT of fraudulent reviews or hype panderers simply by restricting reviews to accounts that have downloaded the demo version of the game. And label reviews as being written by demo downloaders versus full game purchasers.

If reviews become far too numerous, there's always ranking the reviews for usefulness.