How can I remove white residue or spots from dishes and the dishwasher interior?

White residue is usually caused by hard water. Use a commercial cleaner designed for dishwashers once per month, always use rinse aid, use high-quality fresh detergent, and consider using a detergent booster. To remove spotting, run a vinegar rinse by placing 2 cups of white vinegar in a glass measuring cup on the lower rack and running a normal cycle without detergent or heated dry.