The Cable Guy Syndrome
In which viewers go to see a movie with the expectation that the movie is a member of a particular genre, when in fact it belongs to a completely different genre.
Named for
The Cable Guy, which was billed as a typical Jim Carey light comedy when in fact it was more of a dark, intense movie.
This movie is also notable as being one of the few movies I didn't watch through to the conclusion. After about 20 minutes I realized I was just waiting for it to end, and since I'd rented it, I wasn't bound to see it through.
It is also worth mentioning here that
Matrix Revolutions falls into this category, being a modern comic-book/anime style story instead of the science-fiction opus most people expected.