Yeah, tryptamines and indoles in general tend to have really nasty aroma. 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.
Skatole can also build up in the meat of pigs, especially male adult ones, which is why some pork meat doesn't taste right. This is probably true for other meats as well. I've certainly encountered a similar off taste in lamb meat and duck meat before.
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]).
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. They can be hard to remove so people associate skatole with the smell. It's pretty common in chemistry, many chemicals have bad smells from minor impurities. Isopropyl alcohol is a good example, it has small quantities of acetone. Ethanol has small quantities of acetaldehyde. Really pure ethanol smells quite sweet.
Interesting. I wonder if this is one of those things with odour, where odours can be contextual. I believe there are studies where people are exposed to odour chemicals, and their experience was dependent on what they were told the odour was, even though chemically it was the same odour. The most famous example is probably parmesan vs foot odour, which shares some of the same odourants, and they've exhibited this context dependence too, I believe.
But I don't discount your hypothesis. Upon further googling, it appears indole itself(with no groups on it) is also a known strong component in the odour of faeces.
As for boar taint(finally found the English term for it) it seems this is both associated with skatole and androstenone. So now I'm wondering what the actual evidence is that skatole is supposed to smell/taste bad on its own.
Can't find any sources on this happening in non-pigs though. So I'm starting to think the mutton and duck I had were just contaminated, probably by being raised in unsanitary conditions.
A good rule of thumb to avoid meat with boar taint I've found is to avoid cheap, smoked meat. Smoking is supposed to mask the off taste, but to me it just tastes bad and smoked.
Thanks, didn't know this - but from my experience, DMT smoke smelled and tasted kind of plasticky (like when you burn plastic). Did I just interpret the poop-smell differently?
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. So evolutionarily it's useful to just get away from skatole whenever encountered.
So it's not so much that it smells like poop, just is as revolting in some more general sense. And DMT probably has a lot of bitterness to it(can't remember what it tastes like, honestly, but I remember its cousins AMT and DPT being intensely bitter, though I didn't vape them).
Weirdly, skatole also smells nice in very small quantities, and is apparently used in perfume.