I am a real estate agent and I can tell you that several of my clients have not been able to get financing, and they are earn a moderate income.
what kind of down payment do they have?
Are these clients creditworthy, under "old school" credit standards? Down payment, debt to income, payment history, employment history, assets?
Expand on that when you can. Do you feel they are looking out of their price range? What is their income/debt ratio? What kind of down payment do they have?