What is smell?

[NAKID]

But, you did have many thousands of parts per million of CH4 and H2S, among other vile smelling compounds

H2S is actually colorless and odorless though. Deadly in confined spaces.

I'm not sure that H2S is excreted by the body. It is produced by the decay of the feces itself, so it probably isn't present in the body in any real measurable amount. It is however found in sewage treatment plants and marine sanitation devices (shipboard CHT (collection, holding and transfer) tanks)....