I once knew a window cleaner that produced the worst results I have ever seen. He never possessed a scrim, and use old bar towels he cadged from a pub.
Over the years, this guy must have lost half of his new customers after the first couple of cleans, but he eventually ended up with a full round of non complaining customers and no stress.
If I take my car to the car wash, and pay a fiver, I don't expect to have my car valeted, and it would be unreasonable for me to do so, and that IMO is what this lady was, totally unreasonable, bad day or not she would have been dropped.
I have persevered with a few unreasonable customers over the years, and then find I am spending twice as long to do their windows for no extra cost. I used to worry in case they could find something to pick on, it's just not worth the effort or stress. DUMP and move on.
I never canvass for work, it all comes from personal referrals from existing customers. Dai