Me and the dog walked up on a guy using one last fall. We were after squirrel, he was late season archery. I knew there was something strange in front of us because of how the dog was acting but it took me a while to "see" his blind. He had it stretched out in a line. The top was angled forward toward us so it reflected the leaf litter of the ground in front of him perfectly. It reminded me of the alien's camouflage in the movie Predator.
It didn't fool the dog at all, but my eyes were completely fooled.
