Wonder why after we give our dogs a bath they will go outside and roll around in the dirt or something even worse?
There are several theories why dogs roll in smelly stuff. One is that it's an instinctive behavior harkening back to pre-domesticated days when hunting dogs would bring back information about available food to the rest of the packs. The thought was that if they found decaying fish, perhaps fresher fish could be found nearby. Some modern-day dogs may have retained this behavior even though it has lost its once necessary function.
A second theory is that dogs roll in foul-smelling material to provide an olfactory disguise to improve their hunting opportunities. What better way to catch a rabbit say, then to smell like one, even a dead one, rather than like a dog? This canine camouflage technique also may be employed to hide their doggy scents from other predators.
Unfortunately we don't agree with our dogs with what smells good or what smells bad. We carefully shampoo our dog, rinse them, towel them dry and brush them. Finally our dog is clean and smelling sweet. To the dog, the shampoo is a dreadful stench that needs to be disguised immediately. That would explain why dogs will dash outside and roll in the dirt. Some will even roll in poop to cover that awful shampoo smell. It's their version of a high-priced perfume or cologne.
Maybe we should create a shampoo that smells pretty bad, not something that we cant stand just something that an incense would cover and then maybe our dogs wont throw a good bath out the window! Yeah that probably wouldn't work either...