There were several long and involved answers but the one that blew me away was---
"The smelly substance in excrement is skatole (3-methylindole), and it is the substance to which the human nose is most sensitive on a per molecule basis. No doubt it is present in feces because it is a breakdown product from hemoglobin that enters the gut via bile. We have evolved to be repelled by it because excrement transmits disease and we should steer clear. However, skatole doesn't always trigger the disgust reaction in humans, nor is the reaction shared by the whole animal kingdom. The substance is used in small amounts as flavoring in food, notably in vanilla ice cream. Dung flies are attracted to it, and the phallus-like spadix of the arum lily (Zantedeschia aethiopica) synthesises skatole to attract flies that pollinate the flowers. The civet cat also has glands that produce skatole, presumably to mark territory and repel others. This gland is used in perfumery."
Now I could maybe understand perfume, some of it is rather stinky. But ICE CREAM???? Say it ain't so!!!
I can see some of Ben & Jerry's new flavors now................
"Chunky Chocolate CaCa"
"Banana Butt Butter"
"Pooty Tuity Fruity" anyone