[Help] How to teach the dog to stop rolling in dirt or mud, and to stop digging up the garden?

I'm helping to take care of a female black lab (about 6 years old), and it loves to roll in dirt and mud, and recently dug a hole in the garden big enough to lay inside. She did this when left out on her own for only about 30 seconds; she was very productive.Most of the online 'advice' is "set aside a section of the yard where the dog is allowed to dig". This "solution" is totally unacceptable (and "do the opposite of what you require" is a retarded answer to the question); the existing garden is small and at the edge of the house; there's no place to set aside for digging, and the rest of the yard is fine as-is. Additionally, the entire house has new carpets, and I'm not about to let the dog track mud and dirt all over them. The guides do say to NOT rub the dog's nose in it.The dog has a lot of room inside the house (upwards of 4000 square feet) and has access to sufficient exercise; usually my walks or runs with her are done when she lays down or has gotten tired. This isn't attention-seeking behavior, because she will do it when left on her own, and she is relatively independent anyway. Even when I take her to a dog park to play fetch, if she spots a mud puddle she will almost invariable run into it and lay down - to the amusement of the other people there. She will also do it regardless of her temperature needs; I've learned her behaviors in that regard and mud isn't (just) a way for her to cool down.(the rest is backstory and venting, feel free to ignore it)The dog was a rescue dog when it was a few months old, but it's been with the family for more than 5 years. The owner hasn't trained her sufficiently. I'm actually asking because I got into a fight with the owner when I said that the dog should be trained to not do this, and when I asked how to train her, she became a bigger problem than the dog. I'm the one who taught the dog to sit and to come (using treats and positive reinforcement, of course); but I don't know how to train a dog to not do things. I asked "how do you teach her to stop digging? Are you supposed to shove her nose in it?" (this was immediately after getting the dog out of the hole) and she shouted "that's not how you train her!" (I hadn't done anything to the dog at this point; it was an honest question and I was asking her because she should know how to train her own dog, and I've not done that for anything else - hence why I look on the internet for known best practices or ask someone who should know (and before anyone tries to talk down to me, I repeat that this is why I'm asking on the internet)). I asked her "So... then how do you teach her?", to which she repeatedly shouted "THAT'S NOT HOW TO TRAIN HER!!!!!!!" Based on her inability to say any way to actually train the dog, it's clear that she doesn't know. So part of this post is written due to the anger at the relative shouting at me when she doesn't know how to train her own dog.So, what's the accepted way to teach her to stop getting dirty? via /r/dogs http://ift.tt/2swySfq