Medical examiners are still normal people who can feel grossed out on examining corpses but more so with living patients that present disfiguring body conditions. I personally didn't have trouble dissecting a corpse and examining the anatomy. It's part of the learning experience. In my opinion, dealing with dead bodies is better than opening up live people and then figuring out how to surgically fix them.
With corpses, you only need to figure out what happened to the person and how they died. It's never the same with a living person where your objective should be making them feel better after a surgical intervention. The corpses become disgusting when you know they had infectious diseases tied to their history. No matter how disfiguring a corpse is, it's still dead and can't talk back. So no problem cutting it up and figuring out it's secrets. You'll get used to it to the point you can talk about it during meals without flinching.
At first a medical worker or doctor have some disgusting sense for corpse but as he keeps on in the duty, corpse becomes more of obsolete as he encounter many in his course of discharging his professional duties. At first I felt more of pity to dead bodies than being disgust and as I began to have various encounter with dead bodies, I became familiar with it in a less than and I no longer have that feelings of pity neither disgust to corpse though I try to keep a professional conduct in my operation.
Why most people will find corpse disgusting is because they don't come across it as often as the doctors do. When one come in contact with what he fears many times, it get to a point when he doesn't find it scary again. It becomes a regular thing because of the exposure he has gotten from the times he has come across it.