Might be. But not everything can be bought by money. Imagine if it is true, and one particularly morally strong gaming site decided to report on a publisher's attempt to buy high scores? Or it does not even have to be morally strong, the amount of revenue that a gaming site can get from visits for a news-scoop like that, easily outweighs manifold any revenue they would get from bought reviews: It would be DEVASTATING for said publisher and it would lose far more money than it could earn by buying scores, possibly even go bankrupt. And all publishers know this. If it is indeed happening, I think it is happening in extremely small circles, and that most reviews are not bought by the same publisher.
Another interesting question is, how come not a single ex-reviewer has ever talked about this (as far as I know)? Maybe they are threatened on their life to silence, but that only makes the theory seem even more unlikely.
i guess you missed that whole "kane and lynch gamespot scandal" a couple of years ago. it was anything but "devastating" for eidos. K&L sold relatively poorly, but a couple of weeks after that everything was forgotten and then business as usual for both gamespot and eidos. that's the modern gaming industry for you. "decline" is the understatement of the century