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 haven’t read Coleen Hoover, but I’ve handed out 5 star reviews to my trashy, guilty pleasure books before. Like if I read a book that really pulls me all the way through it, that’s a 5 star book imo. It can also apply for works of great literature that tell something powerful, but I’m not holding on to my 5 stars for the kind of books I read once a year or less frequently.
Murderbot Diaries, the Scholomance series, and the Saint of Steel books all get 5 stars in my goodreads