Rotten Meat is the absolute worst.

Rotten gum disease breath is bad too.

Also, Parmesan Cheese....ohmygosh, smells like baby vomit!!!!!

-gasoline...i have to haul when i fill up my car.
-canned beets
-that nasty hair removal cream
-vomit-I guess this is a given, but simply smelling this will cause me to regurgitate as well.
-the smell of a fraternity house after a party-that ash/warm beer smell.
-mildew in clothes... you know when someone leaves their clothes in the washing machine too long?
Unfortunately some guy who was sitting in front of me in a poli sci final left his shirt in the machine too long tried to cover up the smell by ODing on some foul cologne. It was by far the most repulsive odor I have ever had the displeasure of smelling.

Paper mills! Aaaaack! Houston is full of them!

Wow, where to even start on this one?! Let's see. Whoppers with onions, they make the whole room smell like B.O.; and, well, B.O. itself isn't exactly pleasant either; pizza with parmesan cheese (puke!);burned popcorn; morning breath; coffee breath; smokers with coffee breath; but my ultimate, absolute worst smell ever would have to be the parking garage up at school--a combo of old musty leaves, leaky rancid trashcans, exhaust, and feet. Ahh, it's especially lovely on a 95 degree day! Refreshing!