T.T.
I feel your pain!!! LOL!!! When my youngest girl was between 1 year and 18 months she would put her fingers in her mouth to vomit... the Pedatrician asked what my reaction was, I said I would get upset, he said to ignore the behavior. I thought yea right, your not the one cleaning up puke 5 times a day... but I did and it time she stopped. Then she moved on to the poop. She was QUEEN of poop smearing when she was 2 almost 3 years old. Thank god it was a phase and passed fairly quickly. There were days I wanted to strangel her. Nobody wants to wake up to clean a room re-painted in poo. LOL! I cant tell you how many times she used her poop as a weapon or as a paint medium. She would even poop in the tub. Id have the 3 of them in the tub and one would start screaming "poo poo" and sure enough she had pooped and was smearing it on the bath tub walls. Id have to 1 by 1 wash them off and clean the shower and tub walls. If we punished her for some thing, she would poop and smear it where ever she was in time out; if I turned my back. She would get bored at nap time and paint the walls in it. I finally realized she was feeding off the reaction again. Nothing is worse than poo! I finally stopped reacting and made her help me clean the mess. She hated cleaning it and it was no longer fun for her because she didnt get the "OMG I HATE THIS... STOMP STOMP STOMP" fit from me any more! Your son also might just be acting out, testing what your reaction is.
He could just be bored and experimenting... its a new texture and medium to creat his art. In my little girls case, she has ADHD. She wants to experiance every thing. She thinks its the greatest thing to flood the toilet to watch the water spill all over the floor. Ripping the pages out of books is another favorite pass time. She likes the sound the paper ripping makes. She dosent do these thing all the time to make me mad, she just craves the stimulation. If you find him doing naughty stuff try to re-direct him. Things that have worked for me are: when she floods the toilet I make her help me clean the water up and explain to her that it ruins the floor and if she wants to hear the water we can fill up a cup in the sink and she can pour it out. When she wants to rip the books, I give her paper bag to tear up over the trash can. I know these are not always practical options, and in situations where redirection does not apply and reasoning dosent work punishment such as loss of a favorite toy for the day might be a good option.
You did every thing I did to rid the smell... it just takes time to air out. In a weeks time the smell will be gone.
Patients is the key... Hang in there!