I was considering just not replying to this but I decided that this mindset makes me too sad.

If an artist decides to include something in their work, it is likely going to be relevant in some way.

To use the stupid meme example of "the curtains were fucking blue" your teacher wasn't telling you that blue curtains = sadness, they were telling you to think critically about what the writer chose to include in the text.

"The curtains were fucking blue" can be a valid interpretation, but the issue is when people stop their thinking at that surface level and ridicule any deeper analysis of a work.