George eats his own poo.
He used to be a stray and it's really common for them to do this, I believe it's also something to do with a potassium deficiency, so we started feeding him bananas as well, he still eats his own poo, he is hairier though, and climbs trees much of the time.
My border collies love sheep poo and voles/mice etc, echo what was said about them being scavengers, just keep them wormed, as for rolling in smelly stuff, Morris rolled in a rancid milk carton someone had left on the field on Saturday, now that really turned my stomach.