Shelties are big on this too, but they only do it as a prelude to barfing. Then there is the matter of what goes in must come out. I never once heard someone tell Rusty to go out and scoop the yard. The first time I saw a large roundworm, I committed one of the sins I have accused my dogs of. I still go ape whenever I encounter one of these obscene creatures.
Worms are bad, but they are only an infrequent problem.
Dirt, on the other hand, is a constant problem. No jumping on humans, or furniture, with muddy paws. No rolling on the ground when it is wet or muddy. All dogs will learn to use a hair dryer and brush to carry out Rule No. 3. All dogs will take a full bath once a week and use deodorant as necessary.