The nature of spoof and parody demands that first and foremost the end product be funny. If one were to decide to make a spoof of a zombie horror movie and created a movie with zombies but no laughs, it is in no way a spoof of a zombie horror movie, it is simply a zombie horror movie, and if one also doesn’t pay attention to the gore and the scares and the suspense, it probably would also be a bad zombie horror movie.