I've been working with an excellent beta reader, Alison Kemper, and we were talking about our efforts to make our books scarier, while at the same time keeping the humor intact.
We both do really well writing pithy, sarcastic dialogue for our main characters. You know, those hilarious off-the-cuff remarks a la Buffy the Vampire Slayer, that break up the tension without somehow diluting it.
The difference is that in an episode of Buffy, we're also seeing the big scary monster (so we're scared too), her reaction (which might not be verbal), and everything moves at such a snappy pace that if they dwelled on something too long it would feel awkward rather than more meaningful.
All those things are so much harder to do on paper! For me, I tried to maintain the pacing over all else, so my main character never really had a chance to process the trauma or experience her own emotional reaction. And that meant the reader wasn't feeling it either.
Because that pithy dialogue is somewhat like having the last word--it's so funny on its own that it doesn't leave any room for you to explore any emotional depth. Like one of those movies that you see where you go away feeling it was only a collection of catchphrases, with no actual plot development. We've all seen those, haven't we, where we should have just saved the $10 because all the funny bits were in the trailer?
So I blame you, Joss Whedon, for giving us expectations that novels for teens can have that same mix of scariness, humor, emotional depth, character growth, and kick-ass pacing that Buffy showed us. Thereby making my job a lot harder.