For me, 2 things come to mind:
1) Limburger cheese. Recall way back in 1972 in my teens, babysitting for a Dentist and his wife. Dr. S. would come home for lunch (while I was watching his kids), since his office was about 10 minutes away, only to open some (smelly!) Limburger cheese and put on some Old London melba rounds and then bake/broil in his oven... I had to actually get *out* of the house the smell was soo bad!
2) When my parents cooked their eggs, they always (yuck!!) melted butter in a small frypan on the stove, and when the butter was like browning, they would add the egg on top of it. That smell - no matter what - was the most gut-wrenching smell I recall and would always give me the dry heaves!!! My DH today uses non-stick spray and then some Egg-Beaters... with *no* aromas!!