This is quite a natural behaviour for dogs, although we don't think so. A dog in the wild will instinctivly mask it's own smell. Remember no matter how loving your dog is, it is still a wild animal at heart. So to avoid predators eating it. Your dog masks its own smell with that of something else. I've have had dogs that roll around in fish heads on the beach and that didn't half pong.
The only way to stop your dog doing what comes naturally is to un-naturally stop it doing it by either restraining it on it's leash after it's had a poo or to check it. Never scold it or hit it, remember it's doing what comes naturally.
Just like eating it's own faeces. It may sound and look bizarre to us, but again it is clearing away evidence of it's whereabouts.
Dogs that do that are sometimes stressed or lonely.