During childhood, whilst out for long walks involving evacuation, I can personally vouch for the efficacy of grass and dock leaves. Leaf mould works fairly well as well. I recall some 45 or so years ago, my brother and I were examining some enormous and ancient badgers' setts in Norsey Woods (where Watt Tyler and his peasants' revolt was reputed to have started) when I carefully put my left hand in a pile of fox shit. I used leaf mould to remove it, but although visually it looked as though my hand was clean, it was about a week of constant washing with soap and water before the smell finally dissipated.