|It is thought that dogs may choose to roll in foul-smelling things to mask their scent, just as wolves do. Wolves may roll in decomposing carcasses or the feces of herbivores (plant eating animals) to disguise themselves. They want to cover their own odors so their prey will not be alarmed by their scent. This way, they can sneak up on their prey and have a better chance of making a kill.
Some behaviorists feel dogs may roll in smelly things to 'advertise' what they have found to other dogs.
No matter the reason, unfortunately, some of our domesticated friends have held onto this trait. How many of us have given a dog a bath only to find him running outside to again roll in something foul?