Thanks for the replies. As Mike said, the plug-in air fresheners are a dead giveaway that someone is trying to cover something up. However,this home did not have any aromatic camouflage in use. In fact, they made no attempt whatsoever to hide any of the nasty conditions. That's why I was a little uncertain as to whether to mention the urine smell or not. When there are artificial means in use to cover up smells I always mention the likelihood that they are trying to cover up something unpleasant: musty smells, cigarettes, pets, incontinent Aunt Gladys, whatever. But despite the fact that this home was only five years old and in an upscale neighborhood there were scary carpet stains and easily visible rodent droppings in several areas. The piles of dog hair built up around the perimeter of the rooms would be sufficient to stuff several throw pillows should one be so inclined. The buyer said "We made a lowball offer, and to our surprise they took it." Imagine that.