The driver complaint about the wipers not clearing the windshield properly is often due to problems with the wiper blade itself. Nicks in the rubber and bent brackets that hold the wiper blade insert are some of the most common problems associated with the windshield wiper that does not clear properly. In many cases replacing the windshield wiper blades will correct both of these conditions.
Also keep in mind that the rubber on the wiper blades themselves will harden over time which will reduce the efficiency of the blades and can cause extremely irritating noise. As a general rule of thumb I replace my own wiper blades about once a year whether they need it or not.
When the wiper blades become out of time or do not park low enough or hit a windshield molding this can be a sign of bent parts. Often this can be traced back to the wiper transmission linkage or the arms themselves. The most common cause of bent windshield wiper parts is a driver that does not clear the windshield of built up snow and just turns the wipers on.