I've spent a good bit of time around kids, and I say this as a guy who doesn't even want children of his own. This past summer, I worked for a organization that offers mentoring (kind of like a "Big Brother" type deal) to kids who were referred to us by the Department of Juvenile Justice.
Before that, I spent about three years during college volunteering with a team who went into a low-income community and (with consent from parents) just played with the kids and did some lessons. The kids were anywhere from 5 to 16 and many of them I'll admit were mischievous or downright cruel to other kids. But they're still just kids, and lots of them had some terrible parents (if they even had parents).
Even at their worst, I cannot hate a kid. They don't think like us, they don't know everything we know. Even more, we don't know what's going on in their lives. If you really need to place your dissatisfaction anywhere, place it on parents. I've seen way too much neglect, abuse, and spoiling from parents to ever focus my disdain on a kid.