In my experience, there's three typical reasons:

(1) The poop is unpleasant. I want this out of my diaper. But now it's on my hands. I want this off my hands. The wall seems to do the trick. (Tactics include much more frequent diaper checks during the pooping hours and making it more difficult to get into the diaper. Praise for each successful diaper change where little hands are still clean. No criticism or negative reaction when there's a setback.)

(2) The poop is a fun texture, or the smell is interesting or (shudder) the taste is interesting. (Tactics include finding a suitable replacement such as homemade playdough -- so you can control ingredients and dyes and taste. Something else that works to satisfy that tactile need, or as a reward each day that there are no poopcidents.)

(3) This is a BIG DEAL. Every time I do this, mom and dad go absolutely nuts. They cry, they scream, they beg and plead with me, they fall to their knees crying "Why, God?" They run around ripping sheets off the bed, they attack the walls with sprays and rags. They're animated and it's fun to watch. Sometimes I even get an extra bath out of it. (Tactics including being very non-reactive, emotionless. It's too bad it happened, but you have a gameplan to return the house to a state of health, but you're measured, controlled, outwardly you appear as cool as a cucumber, even if you're cussing up a storm inside. Even showers are a matter-of-fact cleaning at a lukewarm temperature with the wash cloths that aren't as soft and over quickly, with no time to play in the bath, all function, no fun.)

For almost every parent, this is a phase that does eventually come to an end with only the rare setback. But are traumatic as it is for you, the parent, find the zen to say "I will prepare, I will train, I will get through this."

Hang in there, mom!

Sorry for the late response. Sounds like good ideas but it drives me crazy. I have started not getting upset I just clean it up but I be hot inside.

Sorry, I guess my answer is not at all useful then. This is more about not understanding the right away to clean and dispose of it?

Well my son isn't wearing a diaper he is 19 years old with autism. He is really not putting it on the walls only all over the toilet and in the tub. I find face towel dirty with poop so I throw it away and I have also found poop in the trash can. I couldn't figure out where that smell was coming from even after I cleaned it up. That's when I found the poop in the trash can in the bathroom. Have anyone else experienced this?

It happens. Our experience is that incidents get smaller and less frequent with redirection and age. There are a few products that are made to prevent undressing and access to diapers. One is the little keeper sleeper, and the no Pu pant.
It has been a few months since we had a poop incident, but mine like to play with the gel of a wet diaper. We use the little keeper sleeper with great success.