Is there a possibility that a real life bacteria could make your saliva/snot taste like vanilla/cocoa/coffee beans/a distinct flavour and be able to live and exist within the human body that causes disease such as pneumonia.
Is this even physically possible to happen in nature?
Could it possibly uptake sugars from the mouth and excrete them, only slightly changing the flavour of your snot/saliva. How exactly would this process happen?

Or would this be something that needs to be genetically manufactured.