In my experience visiting large facilities, there IS a smell associated with it. It's inevitable with hundreds (or even merely dozens) of animals in the same building. It's not a bad smell, because these were clean businesses that I visited. But just a sort of basic, musky "animal" smell that is easily adjusted to.

When you think about it, it's inevitable that with huge collections of critters, at any given time there is going to be waste material in at least a few enclosures. As well as spilled water....or shed skins that got left draped over a water dish....or any number of other little messes that critters can make. It all adds up to a scent that even us dull-nosed humans can detect. But if the facilities are properly maintained by reasonable, responsible people, it's not an offensive smell at all.