For me, the worst smell i have ever come across is puke.
Not any everyday puke but a very specific type.
Back in primary school they used to give the kids a small carton of milk with a straw at lunch time, im not sure if it is still done.
On those really hot summer days we would be sitting in the classroom, leaning back on our little chairs with the sun shining brightly through the window, heating up our little belly's.
It always seemed to be the kid at the top of the class that puked, and it was usually as he ran for the classroom door, ensuring that any escape route from the room was blocked. The smell of that milky puke would slowly drift towards the back of the room where the rest of us had ran in an attempt to escape the foul stench of curdled milk spew.
That is the smell that sticks with you for life. Its worse than dog shit, worse than stale meet and probably worse than the bog of eternal stench.
Whats your least favorite smell?