Robert Rodriguez is a strange director. He is a good director, but he tends to deliberately screw up his movies with some nonsensical events. He did this previously with From Dusk till Dawn, where he would create a quality setup, and then mess it all with lots of ugly creatures. He does the same here, with lots of disgustingness, in a form of people infected with something that turns them into zombies. It's sad mostly because there is nice camerawork, lots of quality acting (check especially Josh Brolin as medical doctor), and lots of quality humor (check the child and mother moment, as well as the first meeting with an infected patient). It's like some sort of 'fuck you' from the director.