Humans have a smell. Unfortunately that smell is pretty fucking disgusting.
Promising review: "Absolutely phenomenal product! I unfortunately happen to live amongst rather filthy roommates, and you better believe that when their door opens, mine promptly closes. The smell that wavers into my room is just awful. I've had the Moso bag for approximately two months now, and can safely say that not once has this happened since getting the product. It's almost as if it's filtering the air in their rooms as well! It's amazing. I'd recommend getting one for each room for maximal effect, though if you're like me and live in an apartment, one is just dandy. If you're tired of your own smells/musk, or whatever wafts into your room from the outside, these absolutely can do no wrong." —Grios
Source : https://www.buzzfeed.com/ignaciafulcher/bathroom-products-thatll-definitely-save-your-relationship