There are many benefits to our sense of smell. However bad smells can be just as emotional as good smells. The physical reaction caused by bad smells is extreme and the following smells are considered to be the worst in the world:

1. Uranus – ‘The smelliest planet’ holds large amounts of hydrogen sulfide, a gas that has a distinct and awful smell.
2. The Shore Earwig – Many people are scared of bugs and other insects but this bug can attack your sense of smell by squirting out a substance with a horrible smell to defend itself. This happens when it is under attack from a predator.
3. The Lesser Anteater – The smelliest animal on earth, which is almost seven times smellier than skunks.
4. Vieux Boulogne – is a kind of cheese and is considered to smell worse than any other cheese in existence.
5. Rafflesia Arnoldii – This flower, which is found all over southeast Asia, is also known as the Stinking Corpse Lilly and its smell is described as that of a rotting and decaying corpse.
6. Durian – is a fruit notorious for its extremely bad smell. It contains forty four odour active compounds, which includes awful smells like rotten egg.

Refs: https://www.worldatlas.com/articles/what-are-the-smelliest-things-in-the-world.html