skatole

Historically, compounds such as indole, skatole, ammonia and short chain fatty acids were thought to cause the odor of flatus.

As for boar taint(finally found the English term for it) it seems this is both associated with skatole and androstenone.

Weirdly, skatole also smells nice in very small quantities, and is apparently used in perfume.

So now I'm wondering what the actual evidence is that skatole is supposed to smell/taste bad on its own.

They can be hard to remove so people associate skatole with the smell.

I think one of the reasons is that they're chemically similar to skatole, which is an indole chemical that's one of the main components of the odour of faeces.

So evolutionarily it's useful to just get away from skatole whenever encountered.

My theory is that in the synthesis of skatole, you end up with a lot of indole impurities that smell like feces even in small quantities.

Interestingly, I've smelled pure skatole in the lab and it didn't smell bad at all, it smelled like mothballs (not surprisingly considering the structural similarity to naphthalene [moth balls]).

I think it's just like that because skatole is only one of many odours in excrement, but it's the one that makes in uncomfortable and makes you want to get away from it.

This is a Harold McGee thing, originally, and skatole is a determinant of the gamey or barnyardy flavor of lamb as well; further, it's probably more prevalent/dominant in higher-end heritage lamb than in factory lamb.

A derivate of that family is Skatole [1], with its name appropriate to the fact that 1 gram can stink out a whole factory hall (at 0.001446 mg/m³ stink tolerance [2], 1 gram stinks up to 714.000 m³ of volume).

The reason seems to be extra sensitivity to a compound aplty named Skatole.

Skatole can also build up in the meat of pigs, especially male adult ones, which is why some pork meat doesn't taste right.