What makes you stop reading a book?

I’ve read Harry Potter and you, sir, are no Harry Potter.

That, essentially, is what many readers were thinking when they dug into “The Casual Vacancy,� the first adult book by Potter author J.K. Rowling. It’s one of the five most-abandoned books on Goodreads.

Goodreads has parsed its data and polled its users to discover what makes readers give up on a book, and, conveniently, created an infographic that presents the results.

There’s something a little schaudenfraude about an unfinished book, a little slowing-down-to-see-what-happened-at-the-car-accident. Why would someone who likes reading -- Goodreads users are people who find reading to be good fun -- set a book aside? What horrors might it contain?

Maybe handcuffs. Another of the books most likely to be left unfinished, E.L. James’ erotic romance “Fifty Shades of Grey,� was a bestseller that didn’t turn everyone on. “I am embarrassed for all of us,� one reader commented.

But while embarassment is bad, tedium is even worse. The biggest reason Goodreads readers put books aside was because they found them boring -- an overwhelming 46% wouldn’t stick with a book that was too slow. The nearest other reason for abandonment was poor writing, cited by 19% of responders. Other replies were all less than 10% each -- poor plots, unlikable main characters, “extremely stupid� and the like.

While bestsellers top the most-unread list, classics didn’t escape the cold shoulder. Goodreads’ five most-unfinished classics include two of Western literature’s most essential books: “Moby-Dick� by Herman Melville and James Joyce’s “Ulysses.� Perhaps they’re not abandoned but set aside for a later, longer day.

Thirty-eight percent of respondents never leave a book unfinished. About 18% stick with a book for 100 pages or more; more than 43% bail out before reaching Page 100. “I once heard the rule for when to abandon a book is 100 minus your age,� one reader commented.

That brings home something we’d rather not think about: There are so many books to read and only a limited amount of time in which to read them. Is there something noble about sticking with a book to the end? Or is that just foolish if a book isn’t at all interesting?

Of course, all of these things are in the eye of the reader. One person’s poor writing is another person’s page-turner; one person’s must-read classic is, for another, impossibly slow. What makes you give up on a book?

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