A house that is on the market is a lot like a product on the shelf in a store. No matter how good the quality of a product is, if it does not catch the buyers' eye, it will not sell. It will end up on the clearance aisle months later.
In the Real Estate business, it is a similar situation. A house that is not shown at it's very best will end up sitting on the market for months or the price will reduced, or in many cases both.
Staging is the answer to this problem. For empty houses, furniture and accessories are brought in and arranged to give the house "life". For houses that are occupied, small changes can be made to create a spacious and inviting atmosphere.