This may sound a bit out there, but its an interesting scenario that I've had fun thinking about--particularly, if you are into the "scary" side of doctors and hospitals. It sort of redefines that "clinical professionalism" kink.
First off, they distance themselves from their patients not as "fellow people" but something like "specimens." I suppose this is similar to laboratories and what not, but whats to say the two are not two faces of the same coin?
Second, their motive of medical intervention amongst humans would be an interesting one; are they here to poke and prod you into the next step in human evolution, hybridize you with them, or simply because they are curious about your guts work.
Third, they are of a higher-intelligence and would have an intriguing array of medical-equipmet and practices. If they wanted things easily and clandestinely, they would simply bait the subject with a flawlessly gorgeous disguise of the flesh and what not.
I thought it would be an interesting spin on things. Feel free to share your thoughts.