Here is what I did to stop this in its tracks...you can blast me if you think it was too harsh, but I could not stand the thought of having to clean it up again...my son would "paint" the whole room...walls, headboard, comforter, carpet, himself...oh it was horrifying.
The first time I got really upset and he cried and I thought well that would work...but on the second time. When I cleaned him up instead of putting him in a warm bath...I gave him a cool shower...NOT COLD...just cooler than he was used to (about 90 degrees as apposed to 99 degrees)and a SHOWER, because he didn't like showers, he LOVED baths.
He hated taking a shower and that it wasn't a comfortable temperature made an impression, because he never did it again.
It was the brushing it out of his teeth that would make me gag and scrubbing it out of his ears and hair...oh, it was BAD!!
Oh, on the potty training thing...I didn't even go there until after my daughter came and he was adjusted to her...all my friends told me he would just regress after the baby came, I am so glad I waited.
Sending you a great big hug!! {{{{{HUG}}}}}