
Prospective buyers like to, consciously or subconsciously, picture themselves living in "their" new home. They mentally arrange their furniture, hang their pictures, and make their first dinner in the new kitchen. When they see hairs on the bathroom sink (or elsewhere), dust on entertainment center, or smudges on the kitchen counter, they no longer want to live there. Sure, all of our homes get dirtier than we like from time-to-time. We get busy or distracted, or we'll "do it tomorrow". But who wants to move into an already dirty home?! Not many.
Rationally speaking, when investing $200,000, a half million, or even several million dollars on a new home, the immediate cleanliness of it shouldn't really factor in. For $100 you can hire someone to scrub the place from floor to ceiling. What's $100? Well it's about 0.025% of the average Chicago purchase price.
It's also often the difference between getting a second showing on your home and not.