Some girls pee on the seats. I've worked and gone to school in a couple of places where girls pee on the seat. They don't sit down, they hover. So, it gets on the seat. I figured it out when I was in the military. We had to witness girls actually peeing in the cup during drug testing. Yes, it is a sucky job, but that's how I learned why I find pee on the seat in some women's restrooms.