Sega Superstars Tennis, you know, the shitty game that comes for free with new 360 arcade systems? That movie would be so bad it would be hilarious, and could possibly be on par with Plan 9 From Outer Space. Which, in a strange way, would make it good.
That said, I do think some video games can make really good movies too, but, we have to be willing at times to let go of certain elements of the game it was based on. As far as I know, I am the only living human who actually enjoyed Silent Hill. Christophe Gans used the aesthetic of Silent Hill, entwined some of the themes (although admitedly not all of them) into a commentary on the religious right, as well as a presentation of the "question of evil," and frankly I thought it was really well done. Some people still wouldn't have liked this at all, but I think that in many cases if the movie had simply been given a different name, and people didn't realize that it was a video game adaptation, then it would have fared a lot better. That said, I think some really interesting things could be done with Bioshock, Dead Rising, Fallout 3, or a host of other games, but we'd quite possibly have to be willing to view the movie as a stand alone entity, simply embracing some of the themes from the game. However, some game movies are still going to be bad, even viewed as a stand alone movies, both Doom and Alone in the Dark are still horribly shitty movies.