While reading (or listening to) a book, I often think "what is my current rating of this book" to keep tabs on how my mood changes based on character or plot development. Sometimes a book can have a derivative storyline but then toss a super twist at the end that skyrockets my opinion of it. Sometimes I might not like a character, but their dialogue is so well-written that I can't help but appreciate the book a little more for it. The opposite holds true as well.
As I consider books, there are many things that can affect how I feel about it. Obviously. However, there appear to be certain things that will almost always negatively affect my rating. This isn't intended to be an exhaustive list. I will almost certainly be plumbing the depths of my curmudgeonliness as time goes on.
1. Having to re-read sentences to make sense of them.
Somewhere the Super-Official Writer's Handbook they tell you to read your work out loud at least once before publishing to catch the things that aren't phrased quite correctly. Not every sentence needs to be a work of art, but unless I'm reading a book outside my native language, the writing should not impede my understanding of your narrative.
Greater Sin: If I have to read something out loud to sound it out...
Deadly Sin: ...and after listening to it, my husband can't explain it, either.
2. Jumping from topic to topic without transition.
I suppose this is akin to info-dumping. I am not talking about a paragraph about the setting followed by a description of the main character. I'm talking about the main character thinking about their difficult relationship with their mother and then their Spanish finals and then about how they like dragons and then about the Battle of Hastings and then which flavor of ice cream they like and then what they're wearing and then about that strange man they saw and then about their hometown. It's too much for a reader to follow. Individually, I can handle all of these things, but in a string they make no sense.
Greater Sin: Info-dumping in stream-of-consciousness...
Deadly Sin: ...while head-jumping narrators.
3. Inducing laughter - in a scene meant to be deadly serious.
If I'm giggling but the author is trying to be earnest, something has gone terribly wrong. Sometimes it's because the author chose words poorly, or because the scene is so over-the-top. I have a few examples from my favorite dead horse: the Inheritance Saga. First example: I'm sorry," Brom apologized. If he's saying "sorry", I don't think the "apologized" speech tag is necessary. Not the worst thing ever, but once you notice something like that, everything starts to become annoying.
Greater sin: Apropos of nothing, while flying over the ocean, Eragon realizes the world is round. Because reasons. *insert headdesk here*
Deadly sin: Paolini actually uses the expression "dolorous cacophany." Oh, and something about soldiers stamping "their left foot." The paraphrased "dolorous cacophony of their left foot" has become a sort of code word in my household for "bad writing."
4. Forcing readers to use your glossary to make sense of the text.
I know, I know: context defines words. However, if I cannot figure out the meaning through the text and have to rely on the glossary, no matter how trivial, it takes me out of the story and starts to feel like homework.
Greater sin: Bone Season and it's mock-slang glossary.
Deadly sin: Inventing a language and having whole swaths of dialogue in your made-up language only translated by frequent field trips to the glossary. (Yes, this is another swing at Christopher Paolini.)
5. Using serious social issues as a cheap plot device.
Greater sin: In The Warded Man, the sole female protagonist is characterized by her virginity. Toward the end of the book she is gang-raped. Afterwards, she immediately jumps in bed with essentially the next man she sees who happens to be the main hero. Because logic. And cheap plot device.
Deadly sin: Black City for having its heroine metaphorically raped by her not-vampire boyfriend because she touched him and got him excited. The victim-blaming is supported by the text instead of being discounted.
Do you have any "you did not go there" things that automatically discredit a book?