Maybe suggest to her afterwards if you think the quality is questionable that because theyve not been done for so long it can on occasions be nigh on impossible to get 'em gleaming on the first visit.
I had one today where the old boy must have discarded his chip fat out the back door; it was all over the doors main window. Couldnt get it off, so I asked him for a kettle of hot water, that shifted it, but took a few tries. Its not always easy and his windows are done 6 weekly.
Matt