As we use non-polarized plugs here in Austria I can say that I never got problems with any kind of appliances. My printer is imported from the US (nice thing: The printer was designed to work on both 120 and 230V, but the power cord was rated for 10A 125V, the previous user just fitted a new plug). So in everyday use it makes no difference.
The only thing I ever saw that wouldn't work if polarized incorrectly was a hardwired gas heater.
