Dogs that have a body odor even after bathing may have a bacterial, fungal ,or yeast problem with the skin. In order to determine this a skin scraping,swab or tape impression, would have to be done. This can be done in the vets office and is not painful to the dog. If it is a yeast or fungal problem then special shampoos are needed, a bacterial infection would require a few weeks on antibiotics. Here is more on odor in dogs.