If your dog is still smelling bad even after you've given them a bath then the bad smell of the dog can be caused by things such as microorganisms like bacteria and yeasts that are on the dogs skin.
After giving your dog a bath you should be sure to dry them off really good using a hair dryer to dry the dogs fur off after a bath.
You can also help get rid of the odor on your dog by using baking soda in the bath to wash the dog with.
The baking soda will help to deodorize the dog and make the dog smell fresher.
You can use cornstarch as well and just sprinkle either the cornstarch or baking soda onto the dogs fur and then use the hose or shower nozzle to spray the dog down and work the baking soda or cornstarch onto your dog.
Then rinse the dog off really good and dry them off using a hair dryer and towel.