I’ll go with the low-hanging fruit: Mein Kampf. I’ve read it, cover to cover. As a piece of propaganda, it’s good. As an example of good writing? Absolutely not (though I will admit I have only read it in translation). Oh, and the whole fascist, racist, and generally shitty worldview of the author that he infuses into the text. And the fact that the author is literally Hitler. You 5-star that book? You’re a Nazi. Period. And as a Jewish person, I don’t look too kindly on them.
I genuinely love Nabokov’s style, and I wanted to like that book. Anyone hard slamming the book or him as an author because the subject matter makes them uncomfortable misses the point, I think.
I’m more worried that they would have liked it too much or identified with the protagonists.