I know this topic has been beaten to death on here, but I recently experienced a situation while on a 10 day section hike that I wanted to share because of the way in which in ended...
My partner and I pulled 21 miles on the first day of our trip because it was raining all day (this was a few weeks ago when Hurricane Matthew came up the coast), so there wasn't much to do other than walk. We had just entered the southern part of SNP, so camping spots were limited and we decided to push on after dark into Calf Mountain Shelter, arriving a little after 9:00pm. I had no intention of staying in the shelter, as I've only slept in a few in over 1000 miles on the AT, but my buddy was dragging and was very much looking forward to getting there, throwing down his pad, and going to sleep. It's pretty much all he talked about for the last few miles in a cold, dark rain. We expected others to be there, and understand that space is first come/first served, but we still figured it wouldn't be full.
But as we walked up, wet and tired, we saw that it was indeed full. Full of tents. Three of them to be exact, one of which was a huge 2-3 person tent. Between the tents and their gear, there was literally no space left. My buddy sat at the picnic table right next to the shelter, exhausted and over it, and let his thoughts be heard, but none of them stirred or stuck their heads out to offer to make room. I went about hanging my hammock and then found a spot for him to set up his tent, which he did, and everything was fine...but it was really frustrating, particularly to my partner. There is no way they didn't hear us come in or hear us talking about it, but they all held their breaths and didn't move a muscle until we left the table. The next morning, they packed up early and we never even got a look at them before they broke camp.
Fast forward a couple of days, and we're taking a late afternoon break at one of the huts before moving on for a few more miles, and a guy who was already set up behind the shelter walks up as we're putting our packs back on to inform us that he was one of the people tenting in the shelter that first night. He said he heard us when we got there, was surprised that anyone else showed up that late, and told us that he "didn't understand hiking etiquette" when he set up his tent in the shelter. He said that he felt badly as he listened to us set up in the rain, that he would never make that mistake again, and he apologized multiple times.
I would have thought that not setting up a huge tent in the shelter falls more under the lines of common sense than "hiking etiquette," however the fact that this dude acknowledged it and owned it when we never would have known it was him was a stand-up thing to do, and tells me that he genuinely did not know he was being inconsiderate. It has also given me pause to consider that sometimes when somebody throws their trash in the fire pit or washes their dishes in a spring or does something else ridiculous like that, maybe they're just ignorant and not actually an a-hole? Food for thought.