this pretty much delineates the three categories:
• bad books i'm glad i read, it's because i learned from them
• bad books i regret reading, it's because something about them is actively stressful—disturbing (or actively triggering) content or exceptionally poor basic writing skill, for me
• bad books i don't care about are mostly just not compelling. nothing especially hateful beyond a lack of especially positive qualities

also absolutely do not ever read the wizard knight please learn from my mistake. there's literally thousands of better-written self-insert fanfics you can read online if you really want to, and most of them don't glorify abusive behaviour

i will, however, encourage folx to look into dickens' work if you're not already familiar with it. i wouldn't generally recommend any of his novels, but his short stories tend to be good and it's worth reading commentaries on a christmas carol just for the history—i'm legitimately impressed by the amount of detail he fit into that one story in support of better treatment for the poor, and a lot of it is hard for a modern audience to pick up on. so decent commentary contextualises a Lot of things

honestly a lot of the so-called classics of literature fit this general pattern—most of them are relatively uninteresting to a modern audience in terms of writing style, and the majority of them are useful tools for developing a contextual perspective on the time & place they were written. the downside, of course, is that it's exceedingly common for them to be really d__n disturbing for a modern audience, especially if one happens to be a minority, since the list tends to be curated by white men

correction: it's exceedingly common for them to be really d__n disturbing for a modern minority audience

from my understanding, most cis white dudes are left unscathed by reading these