Why does my english mastiff stink so bad even after his bath? His skin and coat are beautiful and thick.?

He is 19 months old and approximately 160 pounds. He stays in the house all the time except when going out to potty on supervised walks. His skin and coat are beautiful, shiny and thick. His folds under his arms and legs are clean and show no irritation. He eats Science Diet Sensitive Skin formula and very little table food. He has regular checkups with the vet, etc. He just stinks!!! He smelled like this when we got him from his breeder, but we thought the smell would go away. Even hours after a bath (with gentle oatmeal shampoo) you can smell him when he walks by. He is to the point of making the house stink. Is this something that is common in mastiffs? My pitbull/dane is treated the same way and he never smells at all, even after playing outside. Any suggestions would be greatly appreciated.