I found a couple behind my house on some of our private land last year. As it turns out some neighbors were hunting on the land, which I don't mind in the least, but since they didn't have the decency to let us know they were putting up game cameras and a tree stand, I figured they were fair game for me. So I pulled them down, downloaded the images they captured, mostly not very exciting, a few deer. I deleted the pictures of me coming up onto the cameras, then uploaded some sasquatch and bear pictures and put them back.
So, now I recommend carrying an SD card reader that works with your phone. Keep a few pictures on your phone that will make you laugh to think about the camera owner seeing them when they download their camera. Then make sure to have some fun whenever you come upon one without a sign that tells you it's legit and not just some random hunter or curious person taking your picture without permission.
Go out and hike and have fun!! Mess with peoples minds and have even more fun.