If you've got a teenager whose room is legitimate SQUALOR and you're wondering how they live like that, here's one answer. They don't mind the horrible odor because they literally don't smell the horrible odor.
A new study out of Denmark found teenagers were less likely than any other age group to recognize the scent of sweat and body odor. The researchers say that could be why their rooms smell. Basically, they get used to the scent before they even fully recognize it and realize it's bad.
Teenagers were also the least likely to recognize the scent of soap.
So what CAN they smell? Food, but not healthy food. Teenagers were more likely than adults to recognize the scent of Coke, ketchup, cookies, cotton candy, marshmallows, and candy bars.