Here's an example from my personal experience.
This happened at one of our favorite spots out in the desert. It's wide open BLM land, but the camping spots are limited because it's only practical to camp where the brush has already been beaten down over the years and there's already a ring of rocks for the fire.
We pulled up to our favorite spot where we had told the group to meet us. I picked that spot because of the location and size. In that area, it's an unwritten rule that groups should pick a spot that fits the size of the group, so that you don't have a solo camper in a space that would fit twenty rigs. (We also don't "share" spots. We try to keep at least a football field length away from each other so that dust, kids, dogs, generator noise, music, etc. doesn't bother anyone else.)
So I pulled up to our agreed-upon spot and started to unhitch, but the campers who left that morning and dumped their gray tank right there in camp. There was a huge puddle that wrecked that area, and it was full of food particles (bits of salad, pasta, etc.) because the dumpers didn't know how to do dishes in an RV. The smell was horrendous and there were flies everywhere.
We had to pick a different spot and then drive out to the highway to contact everyone in our group and tell them the new location.
All this, just because the jerkwad before us wanted to shed a few pounds for his drive home.