Hi Janet: If you need to get rid of cloudy residue on your drinking glasses, wipe them down with diluted white vinegar, and then rinse them off. You can also soak multiple glasses in equal parts white vinegar and water for 20 minutes to get rid of any spots.
Or, Leave them in vinegar and water overnight to loosen calcium deposits, rinse with water and dry with a microfiber towel. Vaseline or petroleum jelly can sometimes remove light calcium build-up. You can also fill the glass with lukewarm water and drop in a denture cleaner tablet and leave over night.
Check out this site, it may help:
I agree with Betsy. The only other possibility is that they are etched from automatic dishwasher detergent. I don't know of a fix for that
If above techniques don't work, they never do for me, they are etched by hard water and will never become clear again. Soaking in CLR or pure vinegar helps some.