Trust me, pru, I know. I've worked mostly in Title I schools, which is where you see the highest incidents of need and trauma. Most of my students are processing trauma and don't realize it. They act out in explosive ways more often than not.
The key though is to control the energy of an exchange instead of matching it. You match the disrespect, you lose. If you set boundaries and standard of behavior by telling the kid, "I'll help you but not when you speak to me like that," or, "I need you to do X before we can think about doing Y," you tend to get better results, particularly when they see you approach everyone the same way.