Cooking really spicy food can cause everyone in the house to start coughing, even those who love eating spicy food, and even with a decent venting system. Then there is sea food, many preparations of which are going to smell like sea food no matter what you do. Or there are just recipes that involve lots of fish sauce (or any other heavily fermented sauces).

Baby octopus fried in fish sauce stink, even with a vent fan.

Plenty of dishes, and entire cuisines, need good ventilation.

I don’t want to be smelling food when I am not eating, or about to eat.

Have you ever smelled a room permeated by Indian food?