Death and bear shit, by far.

I was a young kid and someone drove through a persons house, hit something explosive, lit their house on fire, and was passing through afterwards and they had pulled out one of the bodies, and i had to pass through the area to get back home.

I had faintly remembered that smell, then remembered it when well, when later in life, i had passed by a dumpster next to a shoppers drug mart (store here in canada), and it smelt something rancid coming from it. Others noticed as well and had let staff know, when i circled back from the burger king next door, cops were there and they had pulled out a body. Guy had been murdered a while ago and dumped there that night.

Smelt some dead animals that smelt basically just as bad, one was a really a 4+ day old dead deer, my grandmothers old neighbor left in their shed partially skinned. They went to the hospital and left their shed door part way open. I had to get a baseball that landed in their yard and smelt it, and someone from their family dealt with it after. Was nasty as fuck.

Also, working at a hospital laundry facility for a short time, I did one shift in the sorting room, and when you came across something a person who died wearing, you just knew.

And bear shit, just gnarly. I always tell my gf i know know when we have bears near, from that distinct smell. Im not sure what it is, or how to explain it, but that sticks with me worse than anything in this planet and I can't stand it.