About 70% of my home building business consists of spec homes. A spec home is simply a home that is built without a buyer. It is more risky to build a home that isn't pre-sold, but it sure is easier, quicker and generally turns out nicer. Most of the risks can be minimized by choosing a good floor plan and making sure it is built in a good location. However, sometimes a home can sit for a while before it sells. When that happens, there are a few things I do to get rid of it. I rarely sell a house before it is completed and cleaned up. I think it is odd that so many builders get a house most of the way done, but then they don't get it cleaned up and presentable. Cleanliness sells!
Another method that really helps is to buy a few pieces of furniture and decorate a few rooms. I have a friend at Ashley Furniture who gives me really great deals because I am a repeat customer. They have a great selection on line www.Ashley.com. It is amazing how much different a house feels with a few furnishings. Often I tell the people that the furniture is included if they close within 30 days.