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.
The Alchemist isn’t a bad novel, but any time somebody say’s it “changed their life” I just think to myself…you need to read better books. I have read plenty of pulpy sci-fi and fantasy novels that have more philosophical depth than The Alchemist, it’s not at all a unique standout in that regard.