Last week I had something similar. I knocked the door and the owner looked over the counter from the kitchen to the living room, saw who it was and quickly pulled her head back. Then I could see her hands making sandwiches on the counter.
I knocked three times, got no reply, so I have decided to leave it till next time. She has been a great customer for seven years, and did something similar a couple of years ago, but I found out from her neighbour that her husband had walked out on her for another woman the same week.
Let's see, I will knock again, but won't do the windows again till I get some money.
Colin