How do you respond?

A coworker in the office next door to me recently overheard me talking to another coworker about building my new chicken coop. He interrupted from the other office and quite loudly too, 'Chickens are nasty!'.

I know we have a similar thread titled dumbest things people have said about your chickens and this would definitely qualify, but what I'd like to know is how you guys respond to that stuff? Our convo went something like:

Him: Chickens are nasty
Me: Uh, no they're not.
Him: Yep. Chickens are nasty.
Me: Not mine. They're beautiful healthy birds.
Him: They poop every where
Me: They poop? so what? so does every animal
Him: They poop every where
Me: Mine poop on dirt. Poop breaks down and goes back in to the dirt. Beautiful grass grows there. No more poop.
Him: Chickens are nasty.

I gave up at this point. But seriously, how do you respond to someone like that?