What Cookey is talking about is also known as tissue necrosis (which is the medical name for tissue death). For what it's worth this is an ENT or head and neck surgeon direct visualization exam and/or scope.

As David stated, a nasty infection could be the cause as well.

I have to admit that my RO did VERY thorough oral cavity exams but she also specialized in H&N cancer at a major CCC.

This odor would be quite prominent, far over the top, than bad breath or halitosis. In a totally different league than so-called cancer sniffing dogs. They wouldn't have to have scent capabilities 100X more sensitive then human smell for this odor. It would probably overwhelm their sensitive sense of smell.

And your mind certainly can imprint scents. I still smell the burnt flesh from a nasal cauterization (for a nosebleed) I had, as a child, whenever I get a cold.