Let me give you an example:
Imagine you're watching a traditionalist film and, suddenly, halfway through the film, without any foreshadowing, all the characters in the film turn out to be aliens. Can you like that? Yes, of course. Taste is a personal and subjective thing (since it depends on the subject). However, objectively (since it depends on the object), that's a mistake in the narrative structure. Why? Well, because the plot needs to be coherent, and if you haven't foreshadowed that this could happen in the first act, it doesn't make any sense for it to happen in the second.
Truly, surprising people like that is cheap and very low-level. Bad Hollywood movies tend to do that. Why? Because most people don't give a shit. And that's fine. If it's fun, it's fine. But if someone points at you and says, "Hey, that's a script flaw," then they're also right. Does that mean you have to stop liking the movie? No, of course. But if you tell me that script is well-made, I'm going to laugh at you. And rightly so.