Metacritic, a leading games database website, have been quoted by CVG confirming that they have scored off certain websites for 'corrupt practises,' as well as claiming that certain reviewers 'can absolutely be bought.'
This of course raises further questions, namely how often is it done, how consistently, how wide, and to whom?
Strangely, publishers haven't exactly been falling over themselves to make comment on the issue when enquired upon, but it is hard to believe that there aren't a lot of instances of this happening. Many before have confirmed the importance of a system like Metacritic for software sales, whilst game reception obviously makes a big difference to sales; the difference between a 89% and a 90% score can result in thousands more units being sold.
With this in mind, it is no surprise that reviewers may be offered various incentives to increase their scores, whether it be directly financial or, as more often in the case of smaller sites, offers of review copies and a closer relationship.
Even when writing music reviews for the local student media in Glasgow, I was offered incentives at gigs and through contacts to be 'kinder' to certain labels and musicians. These ranged from things like free tickets, CDs etc to full blown offers of cash in hand. Although I did not take them (it's much more fun to slam a poor artist, and I would lose integrity in a close-knit scene), I know of those who did, and in other forms of media too.
As such, for such a thing to not be happening in a multi-billion dollar industry as cut throat as that of games is unlikely. Sure, there are subtle ways of doing it, and different ways to hide it, but next time you see a score which takes you aback, just remember it might not just be personal preference.