Having lived in these areas for most of my life I can tell you it's often only specific low quality chains (Church's, Grannys, Jack in the Box etc...) or these "chicken wing/chinese food" shops that basically just fry up the worst meat and slather it in sugar sauce.

I recall in high school, peers of mine would simply eat a bag of Doritos for lunch - as even the classes like Home-economics were largely just holding cells for teenagers until graduation.