My wife and both daughters are allergic to cats. I always had a cat when I was a kid, but now I realize that a cat house (he he he, not the classical definition) will require a lot of cleaning before my girls will be comfortable living in it.
My youngest daughter has always loved cats and wants one of her own.. until she went to spend the night with a friend. After nuzzling their cat, her upper lip swelled up and her eyes swelled closed. My wife can tell if a house has a cat living in it the minute she walks in the door, as her eyes well up and she gets a scratchy throat.
So while we love cats, their presence in a house is a deal-breaker.
I recommend that you remove any animals and have the house thoroughly cleaned by an expert in animal dander removal, before showing it; unless you are willing to throw away a sizable chunk of the market.
I have been excited about a house before, only to have my wife veto it due to cat dander. The last two houses we bought were brand new, solely because we couldn't find an otherwise dander-free house.