That is exactly what I was going to say. Check for a yeast infection. I sold one that started smelling so bad he was banned from the house. The owner's vet said to put him on pred for the rest of his life. I was heartbroken.
Instead they took him to the veterinary hospital of the U. of PA. They diagnosed him with a systemic yeast infection. He was put on ketaconazole and soon returned to being the house dog they wanted.
Not sure what a moldy smell is, it possibly is a musty smell. First of all dogs sweat through the bottoms of their feet. Feet can be washed just in a small bucket using an antibacterial soap like Lifebuoy or other similar. Lather the foot and just massage the area well. Then rinse well and dry with a towell. Also their bedding can get very smelly in a short time. We use pads and rugs and blanket for each dog area in our kennels in the basement. Other ones outside including old quilts for then to hang out on. So those two things make smells. Then the other thing is their ears. They would be cleaned periodically with Epi-Otic or a mixture of white vinegar and water.
I had that moldy smell on two thick coated Labs. Bathing didn't help. I quit giving them fish oil supplements and bought a gallon of DocRoys Hydro-Clean shampoo that someone suggested. The mother and daughter don't have that smell this year and they swim several times a day.
