If you’re cleaning and still seeing cloudy spots on your glassware, you probably have hard water. As with most stains, the longer it sits, the more difficult it is to remove. There are cleaning products that can help remove the mineral buildup from surfaces or run dishes through the dishwasher again, this time using a rinsing agent. It can also help to increase the amount of detergent used a bit. On surfaces, look for a cleaning product designed to tackle hard water stains and follow the directions on the label.