I don't believe anything can be done about rolling in smelly things. This is a natural behaviour. Wolves will roll in droppings and on dead things to cover up their scent so that their prey is easier to hunt. Some dogs still carry this instinct today. The only advice I can offer is to poop scoop right when your dog is done pooping, and keep your dog onleash during walks and don't let him near poop or dead things. As for eating poop, this could be an obsessive thing, or he could have a nutrional deficiency (what kind of food does he eat?). Some dogs just like the taste. Just do not let him have a chance to get near poop. It can make him very sick. It can give him worms, pancreatitis, gastric problems...The dog could give someone toxoplasmosis...You can try spray suited for making a dog stop eating feces, but it's not usually very effective. Prevention is the key.