My old man would have a fit. He unplugged everything except the fridge/freezer before going out or going to bed. I don't but I do switch everything off at the plug.
Depending on the length the vent needs cleaned also. If it just goes directly out the wall to the outside it can be cleaned out by just reaching in and removing the buildup. If the vent goes any length, up through the roof etc. that can be cleaned with a rotary tool and a vacuum. Home Depot has a kit that comes with a set of flexible rods and a brush that you attach to a drill to clean out the vent. Also the termination needs to be clean, screens and flaps clog up.
I never leave any appliances on when I leave. Dishwashers can back up and flood, same with washing machines. My neighbors dryer caught fire right after she left the house, destroying the house and killing her dogs. Terrible stuff.