I've spent my entire life around dogs. I've broken two Labs from digging by burying the dog's own feces in the hole she was making, as suggested by the dog trainer who's basic obedience class I was enrolled in. The trainer was the one who told me a dog won't touch his own feces, and none of my dogs ever have.
True. We did the same thing. The dog was digging a lot and nothing we did stopped her until we picked up her own feces and buried in the same areas where she dug. She stopped.
My broter has a beagle that ate his own.
The way the vet told them to break them of this habit is to sprinkle the feces with adolph's meat tenderizer or pepper.