You should probably visit your local vet. If the dog has only recently aquired this odor it is likely and ear infection or a skin infection. The fabric softeners and other recipies may take the smell away but won' t fix the problem. I would say an ear infection would be most likely, these are very common in labs and if left untreated can cause rupture of the eardrum along with permanant nerve damage. They are also very uncomfortable for the dog. Mange is another common problem that will lead to a very foul odor in a hurry, there should be hair loss associated with that though.