Let's not forget: all male docs are males first and foremost. The sight of a beautiful woman lying back and presenting her vagina to him must have some effect, surely?
Let's just postulate that the percentage of gays in the medical sector is much the same as in real life. Then there would not be that much of an attraction to a female patient, would there?
And other than that, after the first hundred exams, I would think it is just a job like any other.
It is much like being in fashion photography for instance. The first shooting may be an incredible turn-on, with models changing right and left, unconcerned about modesty. But after a while it is just another job. And think of the poor guy doing the cash register at a sex shop. Do you think any of the merchandise holds much appeal after a while?
I'd rather say that all male docs are people doing a job and all jobs invariably become boring and repetitive.