Back around 1970, in my days as a janitor, while attending college, the worst, most disgusting, horrible punishment duty was to be assigned to clean the junior high girls room.
The boys were more destructive, but the girls were, let's just say, "creative". It was totally unbelievable what they would use to do the things they did.
I highly doubt it has gotten any better.
A few years ago, I met a mother and teen daughter discussing whether to use a ladies room, or go to the mens instead, at a Wyoming gas station/mini-mart. I had just used the (filthy) mens room. I said to let me take a peek; and when I did, I told them to never mind; the mens was worse. The daughter said she could hold it if her mother could, so they left.
Yeah, I suspect jr high kids can be awful, altho I don’t recall the bathrooms being bad when I was that age.