A relative of mine buys dirt imported from France to eat as a food supplement. "Homeostatic soil organisms" sound a lot like snake oil to me: they don't need to do any good, if they sound convincing enough to sell anyway. Show me peer-reviewed proof.

Songster Bob, d'ye think by any chance you just had your drumstick pulled?

Sounds like the chicken ad aimed to disgust and alarm, though it's a valid point it raised about the sort of cross-contamination you can get from a perennial kitchen sponge.

Sure, frogprince and David, if you're looking for life lessons, dirt in your spuds may teach you an attitude of acceptance and humility, but I've never sensed metaphor in the "peck of dirt" saying. A humorously exaggerated quantification of the practical limits of hygeine, it's the culinary equivalent of "You win some, you lose some," or "Momma told me there'd be days like this."