I hate preachy, self-righteous books. The ones where you can tell that the characters are simply a mouthpiece for the author's agenda. It doesn't matter whether I agree with the author or not, I don't read fiction for the sermons. And if you love books, chances are that you don't either.
Sure, we love a good message. I love getting to the end of a book and realizing some universal truth. But subtlety is key here. Some people maybe say that authors, especially YA authors, have a duty to shape young minds. But I call bullshit. My only job as a YA author is to tell a good story. I was reading an interview with the creator of the Brit show Skins on his work importing it to MTV here in the states, and one of the things he said surprised me. In essence he said that one of the main differences was that the consequences of the teens' actions had to appear much sooner. If they took drugs or had sex, the punishment must come quicker. Wait, what? Why do we have to punish teens in stories for doing the things that teens do? Yes, teens do bad things. And sometimes bad things happen to them. But there isn't a causal effect all the time. Some girls have loads of sex and never get pregnant or get an STD. Some girls have sex once and get one or both.
So I guess what I'm talking about is when authenticity and the messages we want to convey collide. If I want to show a party scene in which a bunch of kids get high, do I later need to show them getting into a car crash on their way to a late night Taco Bell run? Is it a literary sin to show a youth enjoying a debauched night of drinking and partying without consequences? I drank as a teen and not every experience was bad. In fact, some were pretty damn fun. I'm not endorsing that kids go out and get plastered, but sometimes they're going to do it and it's not always going to have a lesson at the end of it.
On the other side of authenticity are authors who have their characters act and speak, not like adults exactly, but how adults WANT teenagers to speak. And I think if we're talking about literary sins, that ranks WAY above sin without consequence.
Writing is all about making choices. And I may have veered far, far from my point here, but if you choose to write a story that's about SOMETHING rather than about SOMEONE, then you're not writing for kids, you're writing at them.