Prospective buyers may react to the way a home smells. Cigarette smoke, strong disinfectants, insecticides, kitty litter, and french fries have all been known to dampen the enthusiasm of buyers who might otherwise respond positively to a house that would meet their needs.
Be sure that your home passes the sniff test when it is on the market. Many people have a particular reaction to smoke and pet odors, so consider a temporary smoking ban inside your home while it is on the market. If you have a cat box, be meticulous about cleaning it. If your new puppy has ruined a chair, replace the stained chair with a spot-free one.
There are cleaning services which specialize in stain and odor removal. They may suggest carpet steaming and other techniques to remove the offensive smell. Even if buyers are themselves smokers or have pets of their own, they will react differently to the same odors lingering in a home they are considering.