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.
honestly the modern romances or “eroticas”, like those by colleen hoover and emily henry. i tried very hard to get into them, but it’s like seeing wattpad kids grow up.
anais nin and phillip roth are two of my favorite older erotic writers, for reference. i also really enjoy archive of our own fanfiction, even if i don’t know the fandom. you get some ridiculously well written stuff when you strike gold!