All clothes dryers have lint screens. These screens should be cleaned after every load of clothes is dried. It appears the owner of the dryer with this lint screen had not cleaned it since she became the owner of the house that this dryer was in (13 years ago.) Probably the only reason they didn't have a fire was because the clothes did not dry sufficiently to combust. (It was extremely difficult to remove the filter due to lint buildup.)

Photo taken by Ted Gilmour of T.H.E Home Inspection Company, Inc. Vancouver, British Columbia.