Another Angry Womanwhy is it that only some farts smell like poo? it would make sense for all farts to smell like poo or for no farts to smell like poo but there must be a reason why most farts smell like farts while the occasional one smells like poo
Lars Fischer@stavvers Ok, @Jackobli asked me to weigh in, so here I go.
The classic 'farty' smell are sulfur compounds, e.g. H2S. The fecal smell is mainly skatol, an amino compound. Both are derived from amino acid metabolism. That means, you produce more of both if you eat protein-rich food like meat.
Since H2S is more volatile and more noticeable (so most farts smell like farts), I think the actual smell depends a lot on circumstances and microbiome influence on sulfur.