If your cloudy glasses are caused by hard water, you can clean them with some white vinegar. Alkaline minerals in the water are causing the limescale and a mild acid (like vinegar) will neutralise these minerals and dissolve the limescale. This is how you do it: rinse the glass with hot water. You need to rinse it because soap rests can react to the vinegar and leave behind a greasy film. Next, soak a sponge in vinegar and use this to thoroughly rub the cloudy film. Then you should again rinse the glass with hot water. If there’s any of the cloudiness left on the glass, you should give the vinegar a little more time to do its thing. Soak some paper towels in vinegar and wrap the glass with them, both inside and out. Wait for about fifteen minutes and then rinse the glass with hot water again. Your glasses will be beautifully clear again!
Source: Wikihow | Image: video still, YouTube