This is the kind of movie where the filmmaker hopes to shock you with sickening carnage and violent amorality, while at the same time holding himself carefully aloof from it with his style. He would be more honest and probably make a better movie if he got down in the trenches with the rest of us. The desire by the filmmaker to have his cake and eat it, too. Note carefully that I do not object to the content of his movie, but to the attitude.
Content is neutral until shaped by approach and style.
The head lands in the hot dog relish and keeps right on screaming. Now let's deconstruct that. That wouldn't have occurred to this movie. This is precisely the same construction used by many serial killers and heads of state, who use language to separate themselves from the consequences of their actions. Araki may not have been thinking of Leopold and Loeb when he made his movie, but I was when I watched it.