Most review sites try to rate games like assignments in schools (American schools, at least). For some reason bad games tend to get ratings like 5 or 6 out of 10 because 5 is considered failing. If there's anything they should change, it's the meaning of these ratings. 5 should be average or okay, less should be bad, and more should be good. The only game I know of that has had a 1 rating is Big Rigs: Over the Road Racing. This is of course because it's just a broken mess that didn't finish development. If it did, finish development, it would probably be a 4 instead of a 1.
That said, I don't believe in ratings anyway because I don't think it's particularly healthy to sum up a multi-hour-long experience in one number. And there's no real reason to calculate just how shitty something is compared to another, because you simply shouldn't waste your time with anything shitty. After all, both 1 and 4 out of 10 don't sound appealing at all. BUT, there are some games that I believe deserve no credit whatsoever. If I did score, Hydrophobia: Prophecy, SiN Episodes: Emergence, Kane and Lynch 2, and Star Trek: Elite Force II would all be downright 1s.