I seriously hate them. If it's an action, horror, or thriller movie there should be no goddamn kids, or they should be killed off early on.
Especially horror, where all tension is lost and I only feel annoyance when the stupid kid screams or lets the killer into the house or reads from the forbidden cursed book and dooms everyone else.
I watched The Purge tonight (which is a pretty butt retarded movie in it's own right), but holy shit, *SPOILERED IN CASE YOU CAN'T GUESS WHAT I'M GONNA RANT ABOUT FROM THE SUBJECT OF THE THREAD* The stupid, idiot, retarded, mongoloid, downs syndrome, pea-brained, moronic, ignorant, dense, slow-witted, brain-dead kid opens the doors for a suspicious dude on a night when all crimes up to an including MURDER are legal for 12 hours. FUCK. And they're all like "Don't get angry, he didn't know what he was doing" and that just pisses me off even more.
Kids in general are terrible actors too, so they're bad in dramas too.