The title has a double meaning.
"A Cure for Wellness" does refers to the state of most of the characters in it, yes, but I think it also refers to the people with weak stomachs viewing it. The "Wellness" in this case is the feeling that you've witnessed something that removed any sense of well being in yourself for letting your eyes take in such a thing.
I can't say it's one of the nastiest films I've ever seen (which kinda makes me question the stuff I watch....), but I can safely say it's one of the nastiest released into main stream media in awhile, and to tell you why would spoil most of the fun.
Gore Verbinski practically committed…