I'm going to post one of my pet peeves. There is really nothing to be done about it so I'm just letting off steam.
I HATE graffiti in shelters (and on signs and other things along the trail). I don't really consider this a conservation thing as the shelters aren't natural, but I know how much work someone has put into the shelters and the graffiti seems to be disrespectful of the builders. AND it always snaps me out of my nature trance right back into civilization.
There are registers in the shelter in which we can write and it's pretty much anything goes. So I just don't understand people's desires to write on the shelter itself.
Graffiti on signs is even more irritating.