I had a really bad experience once getting chickens from a farm that wasn't clean. Now, my chickens are in a chicken coop. So of course, there is chicken poop in it, and at this time of year there is quite a bit of chicken poop in there.
BUT this place was something special. For one thing, there was about a hundred (no kidding) geese walking all over the place.
Anyway, after that, I only get tiny chicks from a hatchery or a person that I trust or I get eggs and hatch them out. So then, with a small flock, I don't expect to import disease.