When I got my new chicks spring 2011, nine of them had pasty butt. Since my intent is to raise my chickens as organically as possible, I didn't want a store-bought chemical solution to the problem. I Googled for an answer and found this forum and read up about the "miracles" of ACV.
As a direct result of the forum answers, I bought organic unfiltered and unpasteurized ACV and added it to their water. No more pasty butt... forgot to add it in a time or two and the pasty butt returned in the same exact chicks it had initially appeared in. Added the ACV, pasty butt was gone again.
That right there is what made me a believer!