I went to both what people would consider "Crappy schools" and "good schools".
Crappy schools have an awful student body, many of which don't want to be there, are further behind in their learning than their grade indicates, are disruptive, and teachers have to spend large amounts of time calling security to have students removed or disciplining students. Often, the parents blame the schools and teachers for all their kids' problems.
In my experience, some of the teachers were still trying their best (usually young ones that weren't made cynical yet) but others were too burned out to care much since you only had to look around and see it was mainly hopeless.
The crappy school had fights every day in classes and in the hallways and were fairly violent places.
In the good school (last couple years of school) I wasn't sure the teachers were any more talented but the students showed up on time, listened, did their assignments, and were not violent or disruptive. Honestly, it was really strange to me the first few months and felt probably like when a prisoner is put back into society and they don't quite know how to act at school yet. Any slight I'd meet with threatening behavior to defend myself and intimidate, but I found it wasn't necessary after some time. I hated that school too but I think it was more I disliked a lot of the people there and the reason why was because I was initially resentful of their comfortable, happy life and civility, and just how functional things were. People listened to their teachers and wanted to succeed. I know that sounds crazy, but I was used to going to an insane asylum every day year after year and this was different. The friends I made at the crappy school are the best friends I've had but as the years have gone on many of them are dead from suicide or drugs or have had a really difficult go of it as adults. It all catches up.
I spent my entire school life in the public school system of a large city and I would never send my kids to those schools. It's not really that the schools that are "good or bad" per-se - it's the student body that determines that and that is largely decided by the parents and communities of those children. So much money has to be spent on security (my HS had 10 full-time staff) and discipline that there's not money for "nice things". But, the administration knows they need to hit numbers so kids are passed along if they show up and I knew more than a few kids who graduated and couldn't read past a 5th grade level.