Showing "nice" messy stinky houses

I had the displeasure of showing a house the other day and it appeared a real gem from the curb. Then when we walked closer to the house we noticed a all famliar smell,, Guess what? Cats !! The people with me didnt say much about it, when we opened the door it was a shocking blast of foul air ! The house was messy and the cat residue was horrible. Carpet was bad and just the stench made my socks roll down. I couldnt go through all the house myself, How can a agent take this listing without telling the owner ito have it cleaned up fumigated or whatever first? The area is nice and desirable, needless to say this puppy or feline wont make the most desriable list.. Thats just Realtor abuse. haha