The idiom "never judge a book by its cover" is one that has been ingrained in the brains of people since they were young, and while this metaphorical phrase is generally reserved for holding off judgment on another person, it is also used in a literal sense when looking at the media one wants to consume. Movie posters are generally representative of the films they want to present, allowing audiences a little preview of what they will see on screen. However, there have been many cases where a movie's poster is -- intentionally or not -- misleading, especially in horror.
Source：https://www.cbr.com/horror-movies-misleading-posters/
