We recommend using dishwasher soap without phosphates as those can tend to leave spots. Spots can sometimes be tricky as they may be caused by the hardness of your water instead of your soap. Rinsing with hot water does the trick every time though.If your detergent leaves a white residue, we recommend trying the following:Soaking overnight in water and white vinegarSoaking overnight in water and baking sodaAllowing your cups to air dryIf these methods don’t work, we will replace your product. Email us at support@Silipint.com.