If that sounds fun, you gonna love the story of Joy Milne who can smell the Parkinson's disease.

There are a lot of reports of people, and animals, who can smell some cancers and other diseases. It's not very well studied but I don't think it's far fetched

You can tell something is going wrong at least. I had a university roommate with a hereditary gut issue. I was able to recognize who he inherited from after his father visited.

It's not difficult for many conditions. Digested blood has a metallic and vile odor. Ketosis and diabetes can cause acetone-smelling breath. Kidney disease can cause ammonia body odor. Liver disease can cause a fishy, musty smell. Unhealthy diets and GI issues can cause bad odors.

In the past, I have often wondered what is wrong with people given how badly they smelled in the locker room or after leaving a restroom. Truly unnatural odors.

Wait, can you expand on the ammonia odor? Is it constant?

My sweat when I exercise very intensely, smells like ammonia. Probably since I was 18 (before I played waterpolo, so I can't tell). Normally it does not, only with very intense exercise (zone 4 or 5).

Edit: a kagi search suggested this is normal

May be normal but also no reason to not get it checked out. Or at least mention at your next regular doctor appointment. Kidney disease is not binary and has phases, you might be getting an early warning sign with your sweat. You might just need to hydrate more as you sweat more.

I worked in the kidney industry for a bit after the hospital thing and it’s something you don’t want to mess with. You can significantly delay the need for transplant if you catch it early.

I will mention it for sure, thanks. It's unlikely the lack of hydration, I drink an entire liter if water in 30 minutes workout, lol

It’s sufficiently foul and is heavy in the air, as in you can smell it for an hour or more after he’s left. The foulness reminds me of the GI wing we had, were the hospital put all these cases in a single cluster so as to try and contain the smell. A “GI bleed” has a uniquely poopy smell, that is what I remember quite specifically. Hard to explain other than it is more than a smell, I have a strong stomach and never got sick myself, but it almost makes even me want to vomit.

FWIW, other smells that I recall quite well - child birth, or, more specifically the odor of women in labor (there’s a specific smell some women in labor produce, not all maybe half, that found it quite gross), gangrene and necrotic/rotting flesh, formalin, the morgue (it’s a weird mix of chemicals and rot), all come to mind.