There's nothing worse than a book with a cool idea that doesn't live up to it. I remember reading a book about a boy who had a bunch of cupboards in his bedroom, all of which led to different worlds. How could that be anything but marvelous? But the writing felt so mechanical, there was no sense of wonder. I was so sad.

A badly shoe-horned romance can stop the plot just as effectively as a "look at my socks!" scene could. Even when the romances are fairly well-done, I'm often left with a niggling sense that it's there because publishers require it, not because the story or the characters really needed it. I liked Maggie Stiefvater's The Scorpio Races a lot, for instance, and the romance develops much more naturally than in The Mark of the Dragonfly...but at the same time, I think the book would be stronger without it, because it leaches page time away from everything else.