The area we live in has hard water, bright sun, extreme humidity which all lead to water spotting. Sometimes at home remedies work and other times they water spots are starting to embed themselves in to the clear coat and require a professional to work them out.
I find a lot of times the paint is good and the glass has more difficult ones to remove. This comes from when you roll the windows up and down when either your done washing, when raining, or a sprinkler is constantly hitting you car. At Summer Breeze we have the process to remove them and protect against them in the future. 