Unfortunately as you have to put up with it I think its sounds pretty normal for his age group. I mean if you watch a young child pick there nose and if they dont eat their snot they will usually wipe it on something like under their desk or wall, chair etc. Same with bloody chewing gum. How many school chairs, desks even at restraunts do you see it? It doesn't make it any easier for you I know and I guess the trick will be to educate him about wiping poo around on anything but a tissue, wipes, loo paper etc as it is not appropriate due to the site and smell. Best of luck. I hope he grows out of it quickly and he gets some help for his bowels that works for him.