I work as an after-school tutor in one of the poorest districts in the country. I work with 4th and 5th graders. The biggest problem I deal with on a day to day basis is discipline. Many kids simply do not listen to adults, and because of that, I spend a lot of my time babysitting. I work with 6-7 kids on average, 3 of whom want to learn and 2 of whom I could teach if they weren't distracted by the other 2 causing hell.
Since it's after school and optional, those 2 shouldn't be in the room to begin with.
For all the talk of teacher unions, merit based pay, and voucher systems, none of these will fix the underlying problem. The fix needs to begin at home, and I don't think there is much government can do about that.
You can blame the kids all you want, but a child is not an adult. They are not fully developed, and their understanding of the world is very simplistic. I wouldn't label any of the kids, even the troublesome ones, as "bad." They simply don't know any better because of the environment they grew up in. They don't understand that education is important because they don't see how it is relevant. If you are worrying about getting food every day, it's hard to give a damn about learning language and mathematics.
Personally, for an inner city school, I'd start by instilling some sort of disciplinary program. Get the kids to respect themselves, peers, and adults, then worry about the rest.