As far as I can determine, the only servants mentioned are the "servant in waiting" who takes the narrator’s horse and the valet, a man with a "stealthy step," who shows the narrator in and leads him to Roderick Usher. Other servants probably do reside at the Usher estate, but are never mentioned. The fact that they are practically non-existent in the tale except to mention their quietness and functionality may show that they are distant from the Usher family and avoid contact with the Ushers beyond the perfunctory duties they must perform. The “stealthy step” may indicate the servants’ awareness of their master’s malady and a conscious effort to keep him at ease.
The doctor, on the other hand, is painted less favorably. He is said to have an expression on his face that seemed to be a combination of confusion and “low cunning,” or, in other words, very little intelligence. When he meets the narrator on the stair, he approaches him carefully, almost as if he is afraid. The physician is obviously baffled by Madeline’s and Usher’s illnesses, and is visibly anxious around anyone who enters the estate. His “trepidation,” or nervousness and fear may indicate that he is uncomfortable around the strange family—OR—he is hiding something. Usher confirms his distrust for the physician when he stows Madeline’s dead body in the vault. He confides in the narrator that he fears the physician will steal the body and perform an autopsy on it in order to discover the causes of the family illness. So perhaps the doctor is less than trustworthy.