So wrong in fact, that Gamestop never fired any of their reviewers for dissing Kane&Lynch. And some publisher never threatened to sue some gaming sites for unfavorable reviews for it's new top game with the excuse that they revealed those reviews days before the allowed date. Even though they made them public 2-3 days after it. (This may have been The Witcher, but I can't recall.)
Acknowledging flaws but saying they don't have a negative effect on gameplay/experience is opinion. Deliberately overlooking them (bribery or not) isn't.
That aside, hype, how picky you are and the games you know can affect the review you write.
Regarding hype read this.
Picky-ness: Of course you won't give more than 6/10 if the AI doesn't use cover. Unfortunately, other reviewers may not be so strict.
Games you know: If best game you ever played was Doom 1, it's only natural that Gears of War's cover seeking AI will seem brilliant.
Yes, that last one was a pretty extreme example, but you get the idea.
Gosh, look at what you've done. I wanted to keep away from this discussion.