One user answered, “Don't have to say anything, just a nod.” This nod can mean many things: hello, how's your day? Did you see that? No matter what they are trying to say, it is known by the recipient.
“The smell test is foolproof. We don't care so much about putting our clothes away, so we're unsure if it's clean or dirty. Also, sometimes we skip laundry day, and we can re-wear something as long as it smells fine.”