They do play both versions...

What about Dead Rising 2?
PS3 version has massvie tearing and requires a HDD install. Still the same score.

What about Red Dead Redemption?
PS3 version looks way worse than the Xbox 360 version. Still the same score.

What about Resident Evil 5?
PS3 version looks worse than the Xbox 360 version. PS3 scored even higher.

Most of the multiplat games still look better on Xbox 360.

Wow, people aren't getting it. I'm not saying that the PS3 has to be held to higher standards than the 360. I think that reviewers are perfectly justified in having a favoured console. I also think it should go both ways, which it currently doesn't. Red Dead, Dead Rising and Mafia 2 should be listed as the best multi plat experience, I'm just saying that games like Darksiders and Castlevania should be given the same treatment. Bayonetta, The Orange Box, Mafia 2 and Red Dead should all have their scores lowered on the PS3 versions, because people should know that those versions are inferior. The same should be said for the upcoming 360 ports.  

There is only a difference in score when the lower level graphics affect the game. Read Dead Redemption is the same experience on both platforms, hence they score the same. Bayonetta was so bad on the PS3 that the experience was affected, and so they scored differently.

Graphics are not important enough in a game, so that every little difference between to platforms and how the game plays on these should affect the score of the different versions.

So you think that minor issues that no one except people specifically looking for the problem see should result in minuscule score differences that in the end no one gives a shit about. 

Here let me make it all better for you, no one gives two craps

I guess your right, but it's still annoying. I didn't get Darksiders for a while because according to the reviews, the frame rate and screen tearing was pretty frequent. Then I find out a few months later on Neogaf, that the PS3 version was fine, but the problem had been listed as something that happens to both on other game sites. Reviewers may have played both games, but they score the game with one score, even though the negatives are only on one console, which I still think is a little dodgy. I want to know if Dead Space sounds better on the PS3 or that the contrasts in Mirrors Edge are better on the 360, the current system doesn't allow those things to shine through.

You cant use Metacritic for something like this especially considering how many 360 fan magazines are included in the rankings. 

The issue is now that most reviews use a 10 to 20 point scale which would require something huge to be different or wrong for a lower score and that is rare

Reviews on sounds? Nitpicking graphics? Sounds more like you just want the ps3 to have higher scores.

People obviously do if sites like Digital Foundry and Lens of Truth exists...

Frame rate drops aren't minor issues, it's an issue and it bugs people. Had it been the 360 version that was superior, it would be brought up all the time in fanboy wars, I'm bringing it up because it doesn't help me when it comes to choosing which platform to play the game on. This isn't about the 360 vs the PS3, this is about reviewers chiming in the positives and negatives of both versions in their reviews, which many don't.

What? I just said that I want the PS3 to have lower scores...

The sentence you bolded is an example, if Dead Space sounds better on the PS3 and Mirrors Edge is more colourful on the 360, then it should be listed for the reader.