Just tonite I had one chick with some poop stuck to it, it wasnt pasty butt, more like he sat in some while it was frash and it dried to him.
I just grabbed it with its wings and feet tucked in my hand, and ran it under the faucet with tepid water right on the affected area.
The poop softened, came off, a quick rub of the area and right back into the brooder.
The heat light and dry wood shavings dried him right up, and now hes all good.
No soap, no fancy show chicken, just a cornishx with a shi77y butt.
I shoulda made a how-to video of it for the "pasty butt" crowd, too bad I didnt think of it.