These days I tend not to persevere with books that I'm having a bad experience with. There are just too many good books out there.

Poor writing sucks but even worse is when the author misjudges how much they can expect from the reader. Sometimes things can get 'bad' in a book for just long enough that the reader feels they have risen to a challenge and been rewarded at the next change. Some authors are aware of this and incorporate the dynamic but end up prolonging it too much or over-egging it. I actually feel abused as reader when that happens and end up rage quitting. Unfortunately, deleting an ebook doesn't come with the same satisfaction as burning a physical one in those cases.

The other thing that is a bad experience for me is overly long dialogue expositions, where a character does an infodump to provide background and context and justify the plot. It totally jangles me, bores me and breaks immersion in the story by making me cynical about the authors laziness. An example of this is all the Librarian's waffling about biblical stuff in Snow Crash. Rather than making me care more about the outcome of the plot it just yanked me away from what was a really enjoyable story and setting and destroyed the pace.

BTW, if anyone is interested; Bookwyrm is a fediverse platform for discussing and rating books. Much like a federated FOSS version of Goodreads.