Two actual reasons reviews aren't that credible.

[LordTheNightKnight]

DMeisterJ said:
What does this have to do with the actual reviewers (1)?

It has to do with publishers moreso. (2)

Reviewers just review a game. But their review does have to do with developer incentive, but a reviewer doesn't see that. So why would a reviewer overscore a game, and not make any money off of it? (3)

Off-topic:

This topic (4) is getting old. GTA IV gets a ten, and now reviewers are getting paid off around the world and whatnot. Why does anyone care anymore? Ocarina of Time is back on top, and all is right in the world. Let's move on people. (5)

1. The title says rewieves, not reviewers.

2. The fact that publishers are abusing reviewers tastes still makes reviews less credible.

3. See point 1. 

4. "Off topic", and then "this topic"?

5. Oh, god. Why do you assume this is because of GTA IV and OoT? Couln't the Kane and Lynch thing have more to do with this?  Did you even read the OP, or just make assumptions?