Chocobo Stable

Why it have to be cleaned, when there are no chocobos inside?

I mean, if at least one chocobo is in, it is reasonable it will have to be cleaned, but when is clean and no chocobo, I'd expect it stays clean.

I place the wading pool in the stable so you can't tell it needs cleaning.

It's still full of straw. Maybe it gets moldy.

I get a nervous twitch now when I pass a dirty chocobo stable. I used to clean the one at the apartment building I used, too.

Stables get dirty even without livestock in them. Straw molds and ferments if left alone, dust accumulates, and in the case of the chocobo stable it's an open air stable - wild animals are perfectly capable of coming in and nesting if it's not being used.