That would annoy me so much, i'd go over and ask why shes doing it, and basically convince her she needs to stop as shes probably making the windows look worse than they would if she just left to dry with pure.
Nah, if she wants her dad to pay me to get clean windows and then she makes a mess of them, that's up to her. She can learn the hard way.Her dad has seen how they dry for the last three years and so if she tries complaining about any streaks etc, at least I know why and can tell her then.