But most martial arts have real world applications though, though ground fighting is something that should be avoided as much as possible, because asphalt + possibly glass shards is not a good combo for your health.
Why do dogs sniff? Dogs sniff to identify, for the majority of cases it is to sniff whether or not there is danger. A dogs sense of smell is much greater than that of a human being and it can smell things from a further away distance than many other animals as well as humans.
The saying means to feel that someone or something is suspicious in nature. The source goes back to the use of dogs in large mansions and palaces to warn of rats. Apparently, it's believed that a dog who suddenly stirred could smell a rat.