If they've been currently renting a property since 2009, that can mean they are pretty stable. Often renters don't want to purchase because of their jobs. They may not want to mortgage a house because they can be transferred within a year or two. I had a client who leased a house with the intent of staying for at least 2 years. Then he got a job opportunity he couldn't pass up and moved 6 months later. Have your realtor (or you can do it also) a thorough background check.