
Yeast overgrowth sounds likely. She could bath him in diluted Hibiscrub (which is an anti-fungal and antibacterial wash).
If it is Yeast overgrowth then his diet needs looking at, if bacterial then the source needs to be addressed. Mind you some dog and breeds are much doggier smelling and greasier than others, from the virtually odourless (bodies anyway) Spitz breeds to some of the fragrant Gundogs, and some shorter coated breeds.