The listing data on here can be accurate however often it is incorrect.. This is due to either using outdated 3rd party syndication or the listing agent failed to change or keep the home status current. Like Jason said, your best bet if you are thinking about buying a home is to be working with an agent that works in your area. Good Luck!
Often times homes show up on this website and others that are pending sales, or are somewhere in the short sale process. Your best bet is to contact a local Realtor and they can get you a list of what is currently on the market.
On this website they do not change the status until the property closes, and then they use the terms off market. They don't ever indicate when a property goes under contract. Is there a particular property you are looking at?