Wrong expectations while reading (and what it does to the reader)

Have you ever been hyped about a book’s premise and when you finally read it have realized that it is nothing like you expected? The book could still be good but you’re just disappointed.
That happened to me when I read The Dark Lord of Derkholm by Diana Wynne Jones recently.

Reviews I’ve read and watched about this book promised a fantasy adventure: Mr. Chesney brings tourists from supposedly our world into a fantasy world, what causes destruction and death there, which leads the inhabitants, wizards and all kind of fantasy creatures, to rebel against it. Just read this amazing blurb.

Sounds great, doesn’t it?

Sorry to disappoint you (and myself) but this isn’t about wizard Derk looking for a way out or even overthrowing Mr. Chesney. This isn’t about an amazing tour through a fantasy world. This isn’t even about a nice and lovable man being forced to play an evil Dark Lord. All these things just play a minor role in this at best.

This novel is about a family and how they all play their part in a complicated situation, how they have to work together and how they handle their conflicts. It is a little bit of family drama with a huge chunk of planning the tours.
And that’s not bad. Stories about how a family handles a tough situation can be great and this one was far from badly written or executed. I`m just not much into it and was waiting for my expectations to fulfill themselves.

I was allowed to read about the tours through this world eventually on the last 150-200 pages and plans about overthrowing Mr. Chesney are mentioned sometimes, but before that I had already read 300 or more pages of Derk and his family. 300 great pages that just didn’t meet my interests that much. When the tours finally started, I was even less into the book than before (but I won’t go into detail about that here, if you care about why check out my review

The Dark Lord of Derkholm is a nice parody of fantasy tropes, it’s a great story of family solidarity, offers diverse characters and creative fantasy beings and manages to handle dark themes of war and dictatorship while still staying light-hearted in its tone. It is a book I would want people to read, but for the right reasons.
Personally, I couldn’t enjoy it entirely and it’s probably not a book a would have chosen. I struggle with family drama, I don’t know enough about fantasy literature to appreciate a parody of it, I just wanted an adventure centered about a guided tour in a fantasy setting, with magical creatures rebelling against it.

This made me think about all the other times me or someone else has started a book with wrong expectations because of a misunderstandable review or misleading marketing. Sure, the reviewers didn’t mean to mislead me, they just worded it in a way that made me picture something else or just described how they saw the book. However, blurbs that don’t really represent the book seem to be not that seldom.

How often are there discriptions on the book cover that just don’t fit. Describing a book as a “Thrilling Adventure” that doesn’t really focus on adventure or calling it “the next Hunger Games” with it having nothing to do at all with it at all, except maybe the genre.

I can’t blame the publishers for wanting attention for their books, but wouldn’t it be that much better to market a book to the right audience and therefore having much better reviews and a higher chance of recommendation?
I can’t offer to much insight into this topic but I would like to know:
What were your worst cases into being mislead about a book or just expecting something else?