Oh, they so do. I would kms if I had to deal with that. I guess you're right abou the fertilizer. That is unless part of the dragonkeeper's duties is to potty train the dragons because there was that part of F&B where Aemond pushes Joff into dragon shit, so maybe they don't do drive by pooping. Or they at least wait until they land, so they take poop breaks between flying.