I was about to respond to LordMatrix's post, but Rol beat me to it. I don't think MKWii or NSMB:Wii have bad reviews because someone paid for them to, they have bad reviews because they were reviewed by narrowminded tools
If you get caught bribing reviewers to give your game a good score, I don't think there's anything illegal about it. If you get caught bribing reviewers to give another game bad reviews, there would be blood spilt, and Sony would end up paying ludicous amounts in damages. No company would be that stupid. The game got bad reviews because it's not the sort of game that appeals to game reviewers