Scent marking:
Dogs live in a different sensory world form us. Not only do they learn about their environment and the other animals and people who pass through it by savoring the distinctive scents left behind on the ground, but they also habitually do their own scent marking by depositing urine and faeces and leaving traces from the sweat glands on their feet. When another dog inspects such a scenting post, it is like a human being reading the local newspaper; he instantly finds out which animal has been that way, how old he was, what sex, where he was going, for what purpose and whether the passing animal was looking for a mate, food or a burrow.
The scent of you, his owner, and the rest of the household are important to him, and a useful means of recognition of familiar people in different clothes or unusual place. This talent is utilized by search and rescue dogs who are given a scent – clue by sniffing the sweat on a garment worn by the victim. Human footprints also emit individual smells, and an adult dog can successfully follow a trail on grass up to four hours after it was laid. Many dogs seem to dislike strong perfume, perhaps because it masks the natural scent they need to recognize.
Rolling in smelly substances:
Some dogs, especially Terriers, seem to enjoy rolling in extremely smelly substance, much to the dismay of their owners. This behavior may be a form of scent camouflage which dates back to when their hunting ancestors needed to disguise their own scent to hunt their prey more successful.