IGN gives everything high scores, Gamespot's scores are generally lower, sometimes by a large margin.

Ign is known for giving games high scores that's true but usually their scores make since once you read the review.

Gamespot scores especially when it comes to PSP games seem unfair, they dont even give the system a chance in some cases and in others like dead head fred I really feel they just rushed out the review to get it done.

Syphon Filter Logan's Shadow are had the taste of reviewer not playing the game for fun but work. SF:LS is a much improved game over SFM but DM got the higher score.

Maybe they need to take a lesson from IGN and get reviews for each system .... have a Playstation team, a Nintendo team, a Microsoft team, and a PC team .... also have people who enjoy the hardware reviewing games on a system. If dont like the system your opinion for the game is usually lower. IMO this might have been the case with both the Syphon Filter Logan's Shadow review and even more so with the Dead Head Fred review. A lot of other PSP games like MHF (1 &2), and Brave Story got this same treatment too which is really sad.

*Sigh* What I meant by saying that IGN always gives games higher scores is that you can't logically use IGN as proof that GS is somehow biased. You'd have to use a website that always agrees with GS except when it comes to PSP games; then and only then would you be able to bring another website into this.
The way GS scores everything is by giving editors a type of game that they are very familiar with and usually enjoy. They don't go by systems because as journalists, they should be familiar with any game of the same genre whether its on a different system or not.
In any case, this "treatment" is simply someone stating their opinion, you have yours and they (the editors) have their own. An arbitrary number does not prevent you from enjoying a game; if it does, that's truly sad. Forget about biases, things turn truly pathetic when people start crying over an arbitrary number. Forget about it, and if it bothers you that much, leave the site.
Remember, the PSP is not being reviewed; the game is. If the game is mediocre, then the game is mediocre, that doesn't say anything about the hardware.