In our family we have 'brie in the back of Dad's car' as a smell scale of awfulness.
About five years ago a cling film wrapped piece of brie fell out of the shopping bag on the trip from the supermarket to home and fell into a sort of dip between the back of the seats and the boot floor. The smell started but the source couldn't be found. It grew increasingly worse until it was gag-inducing and we did a full strip search of the car, because it just couldn't be used anymore without all the windows wide open, and found it. Since then it has been used as the top end of a smell scale, so for instance the room-clearing farts that the dog does after he's scavenged some bread are about two thirds of 'the brie in the back of Dad's car'.