Demi Moore makes an ass out of herself in The Substance. That’s not an insult about her performance (which is surprising and playful and heartbreaking). That’s a description of the plot. The way this movie focuses the viewer’s gaze on that butt and various other body parts, then increasingly shifts to shower us with all manner of grotesque body horror, forces us to confront our fascination with flesh and beauty and cinematic voyeurism. 

It’s very effective, and easily one of the most disgusting movies I have seen in years and years. (Again, not an insult!)