On the topic at hand, your hypothesis - my understanding was that refined (carb) products "fed" yeasts, fungi, bacteria, parasites, et al. Not that they contained any, necessarily. However, I admit that I've always been perplexed by the widely held theory regarding sugars. Eg., how often do you observe mold growing on candy?
Yet still and again, of course, I avoid - mostly out of lack of desire for the junk.
For that matter, if animals (pets allowed or kept outdoors as well as most all wildlife) are nearly guaranteed to carry parasites - I want to know where and how they absconded with the fast food, milkshakes, and candybars.