@Karlos
Skatole's not so obvious really. It's a degradation product of tryptophan (a muscle protein). Skatole gives sh-- it's disagreeable odour.
And don't forget cadaverine (pentamethylene-1,5-diamine).
Interestingly, the world's most expensive perfumes are blends of botanical oils with 'base' notes which 'anchor' the fragrance. Strangely, these bases are the stinkiest of things, not unlike those mentioned.
Cheers,
JaX