Basset Hounds are notorious for ear infections, many of which are due to the anatomy of their ear and to skin allergies.
Human ears are very different from dog ears. Dogs do have many different kinds of highly purulent infections of the ears, all with different treatment protocols. So the additional test is warranted.
The fine needle aspirate is a good screening tool, but it is just the initial step in the diagnostic process. It is relatively less invasive than a surgical biopsy and if performed properly can give good results. If a mass is located in mammary tissue in an unspayed female dog, most veterinarians would not waste time on a fine needle aspirate, but go directly to surgical excisional biopsy, thus removing the mass totally, and biopsying the tissue.
Aspiration of benign appearing masses is helpful, and sometimes diagnostic, but excisional biopsy is the most helpful and can be curative.
Thank you for your prompt answer to my questions. I understand better the reasoning behind the tests that were recommended.