[danielbln]

Cigarette smoke is vile, but burned hair is another level.

[Tade0]

To that I raise: crude oil

Unbelievable how its products separately don't smell nearly as bad.

[skissane]

I’ve never experienced crude oil firsthand, but I assume you are talking about “sour crude” which has a high sulfur content, including hydrogen sulfide, resembling rotten eggs or raw sewerage. So-called “sweet crude”, with a low sulfur content, has a less offensive smell, smelling more like the petroleum products derived from it.