I was day-hiking in the rollercoaster section of the AT today and ran into a few SOBO hikers and I chatted with most of them for a few minutes. They both mentioned using their tents in the shelters when there isn't a tent spot at the shelter. They said that lately the mouse situation has become so overwhelming that they won't sleep in the shelter without the tent.

Heading SOBO and being behind most thru hikers they are getting most shelters to themselves.

Is this a normal practice? I'm assuming that when you have shelter mates this is terrible etiquette...?