Counter-intuitive thought for the day: reading a bad book can be good for you.
Yes, really. Let me explain:
From a craft standpoint, sometimes one way to figure out how good prose works can be to look at clunky prose. Looking at someone's clunky Cinderella retelling side by side with someone else's lyrical one may -- if you take apart corresponding passages word by word -- offer insights into why word choice matters and what makes certain dialogue or narration come alive rather than lying (and sounding) flat on the page.
Alternately, if you run into a page or two of text that annoys you sufficiently, it may be useful as a writing exercise to take that specific passage and recast it into stronger, more effective prose -- and then look at the two versions to see where one goes right and the other wrong. (That said, I do not advise using this approach as a means of creating a story you intend to market as your own. Entirely apart from the potential legal issues, dealing with that much bad prose is likely to drive you insane long before you finish.)
But that's only one dimension of the premise. Sometimes a book can be severely flawed but highly provocative in terms of the issues or ideas it develops. There are works that one may not consider "good" in and of themselves, but which are important for the place they hold in the literary or genre canon. There are books that one might classify purely as "popcorn" -- to be read for sheer escape or entertainment value, irrespective of any quality stamp. I've recommended titles in all these categories for the SF book discussion group I co-moderate, and I'm happy to defend any of those choices. This coming Tuesday we're looking at David Weber's first Honor Harrington novel, On Basilisk Station -- which I'm sure some of our members will decry as a bad book. They may (or may not) be right...but I think it's worthwhile for the group to read and discuss it regardless.
Personally, though, one reason I read -- and even occasionally seek out -- bad books is that it helps me maintain perspective. If I only read stories I like, or stories that I expect to be "good", I'm limiting my sample and narrowing my range. I need a sampling of the negative outliers as counterpoint, so that I can better recognize and better appreciate the really good stuff on the upper end of the spectrum.
So feel free to read a bad book this week. And let me know what it was; I might just check it out myself.