Ooh--when talking about organic "sprouts", I thought for sure you'd bring up the contaminated (er, unclean) organic sprouts that killed all those people. And maybe contrast that with the complete lack of so much as a sneeze from GMOs.
That said, I don't see it as a "dirt" aversion so much. I think it's yearning for simpler stuff that they can understand. So many people don't understand the benefits of tech for farmers because so few people farm now. I think people have a sepia-toned image of the past, despite the fact that hunger, famine, and food poisoning due to lack of storage technology used to really problematic. In this way I think it's a lot like the vaccine situation. Our success at solving a lot of these things makes people think the past was better. It wasn't.