Some banks have started using CMA's in lieu of appraisals to value a property.
A CMA is a Comparative Market Analysis and is usually not performed by a licensed appraiser. It is usually performed by a real estate agent who is doing work for the bank on the side.
Many CMA's are performed on a drive-by basis, i.e., the person doing the CMA does not actually enter the property. They simply write a report up showing what similar properties have sold for in the area.
Because CMA's are typically not done by licensed appraisers, we do not consider them to be as reliable as full appraisals.