Get rid of fogginess—and prevent it from happening again.
It's perplexing: You grab a glass out of the cabinet and even though you know it's clean, it looks foggy and dingy. A few things might be going on. First, check your water. Cloudy glasses can develop over time, but often it occurs in areas of both hard water (mineral deposits build up and cling to glassware and dishes) and soft water (due to corrosion). In some cases, your dishwasher might have permanently scratched the surface of the glass.
The only surefire way to prevent glasses from developing a hazy film is to keep them out of the dishwasher. Instead, wash them by hand with a mild soap, rinse thoroughly, and dry immediately.
To figure out if your glasses have fogged up because of your water, soak a small dish towel or rag in a small amount of white vinegar and wipe the glass with the cloth. If the glass is no longer cloudy, then the cloudiness was caused by hard water build up. If you wipe the glass with vinegar and it's still cloudy, then that is etching caused by soft water corrosion and it cannot be fixed.
You can remove the buildup caused by calcium and magnesium ions in hard water by swabbing the glass with acetone (nail polish remover), and then scrub gently with a mild detergent. Soaking the glasses in plain white distilled vinegar for 15 minutes is another effective home remedy.
If you have soft water and still want to use your dishwasher to clean your glasses, you can prevent ruining them by making sure that glasses are dishwasher-safe when you buy. When you run the machine, open the door to allow steam to escape once the cycle has finished, and let your glasses cool before removing them.