When is something "pretentious"?

[downbeatplumb]

Hi,

As someone who enjoys reading, watching movies, etc, I wonder what gives someone the right to call a work "pretentious", be it a movie, book, etc. I believe there is some subjectivity to this. What may be pretentious for someone, may not be for the author or someone else. Now, I am not the elitist who believes only a very specific pool of books and movies can be called art, even excluding other mediums such as manga, videogames, anime, etc. I believe every medium has its own characteristics and can be called art by its own merits regardless of its form.

I just dont want to write something that will be called pretentious by the majority of people. Maybe by a few is acceptable though. Its not like I care what people say, but I just dont want to be treated like a naive kid writing a book.

I have been accused of being pretentious.
One time I remember was in a course and they were on about tastes and trying to relate it to some other concept, which I cant remember,  they went around the group asking for flavours I said umami https://en.wikipedia.org/wiki/Umami this was considered a pretentious "smart arse" answer.

Mostly when I am accused of pretentiousness it is because I am either trying to correct "fact" that someone has stated or I'm trying to be a bit out the box. I am a sponge for factoids.