Just come back from cleaning a year old Cons and the owner asked me to do the insides. Did all the insides then the sun came out and was shocked that the windows were still dirty on the ones that the sun was shining on.
Thought something wrong with wfp, spots
Went back out and did again trad way, spots did not go. Took a closer look and all the dirt was inside the sealed glazed units. Absolutely shocked, have never come accross this before and shody standard of workmanship.
The customer is off to complain to the cons company, apparantly 5th time. There are some dodgy companies around.