Not something I've often, If ever wondered about but got an answer today
I live in a high rise flat, my mom popped round this morning and mentioned there were 2 police cars outside, they were still there hours later, I needed to nip out and get some bits, called the lift, the smell inside, indescribable, to the point I went to the staircase and wretched, almost being sick, I walked down the 8 flights of stairs to see in the foyer a body bag on a trolly with undertakers (or private ambulance) and the police wheeling a body away, that putrid smell in the air.
Today I found out what a corpse smells like. It's something that will never leave me.