A quick and easy way to clean a moldy, scaly shower curtain is to simply toss it into the washing machine with a cup or two of white vinegar and a small amount of laundry detergent (with the machine set on "warm water"). All hail Kim and Aggie!
Clean shower curtains by washing them in your washing machine on a gentle cycle. It will clean soap scum as well as mildew. When washing is complete, just hang the shower curtain back on the rod to air dry.