I had a new custy yesterday of which i said i will clean with wfp, she agreed.Next day got a call there's spots everywhere,me thinking well they where dirty (very) but i did the 2 cleans per window to aviod this. So got up ladder to have a look and there are spots, of which don't come of very easey. Tried trad method didn't do a lot so damp scrim and a bit of hard rubbing and they started to move but not all! I asked if the walls had been treated but this was a no i asked who cleaned them befor ,My husband .Hmmmmm where they there then, no she replied.So does the best i can and goes to the door to see here.She standing there with Mr muscle window cleaner, This is what my other half used . This moves them spots , it did for him. You said that they where'nt there before,I replied.So i now know that it has been a on going Problem,But what will shift them is my main Q. please