I'm an Editor in book publishing. All opinions are my own.
Though I have wide reading taste, I also have weird quirks about what I will and will not read, and when I'm looking for new reading material, a few qualities will often scratch a potential book from my list. Short stories aren't really my thing, for instance. A story just never feels like enough to satisfy me, though I will occasionally give a collection a try. I've also grown tired of novels set in or around WWII, and do not usually pick up historical novels about real historical figures (I've always preferred historical fiction about a made-up protagonist, even if the plot centers around a real historical event).
My one automatic "no," however, is novels written in free verse. Something about a verse novel repels me. I worry I would feel distracted by the format and unable to fall fully into the story, or that I'd think the verse wasn't telling the story as richly as I'd want compared to prose. Maybe I'd think the read was too short and quick. I'm sure this is a crazy thing based in nothing but my own biases, but I haven't felt compelled to give verse novels a chance to date.
What are your automatic "no"s?