Maybe at some point, thousands of years in the past, ancient humans had a more highly developed sense of smell than they do now.
Maybe you could sift through a raft of flavours on the air in a more comprehensive, more instinctive fashion in order to survive.
Maybe when greeting each other you could lean forward and each scent how often the other eats protein, tell how long ago it was eaten, use that information to infer how successful their tribe, how good a hunter they were, how viable a mate.
Maybe it played a part in establishing diplomatic ties, making sure you weren't allying yourself to someone too weak to aid you, someone who would be a drain on your resources.
Maybe it helped you walk the line between survival and oblivion on a slightly better informed footing.
But here and now in the present I think you should brush your teeth.