okay. that might be possible, because my experience isn't universal (and i may have misjudged peoples' meanings). however, even in terms of denotation and connotation, there are correct and incorrect ways to use a word, and since pretentious, when used precisely, does imply "promises more than you can deliver" when talking about music, i think it's very wrong to use it, meaning its other meaning, without saying so.
for example, i might refer to "the mood of this song". "mood", when referring to music, does not mean "a single incidence of sulking behaviour", even though that's technically one definition, and might be what 51% of the populace thinks of when they heard the word "mood".
i COULD use "mood" relating to a song and meaning the non-musical meaning of "a single instance of sulking behaviour" (like if the song was about a pouting guy), but i would have to add a clause making that clear, and should not use that meaning without a qualifier.
same with "pretentious" and art.