There is a story that has been doing the email rounds for quite a while that goes something like this. There are variations regarding the actors but the essence remains the same.
A young couple move into a new home.
The first morning, the lady looks out of her window and sees her neighbour’s washing hung up to dry. She remarks that the washing has been ineffective and the clothes are still dirty. She wonders aloud to her husband if she should walk across and share her own washing secrets with her neighbour.
This repeats itself for a few days and one morning, she finds that the clothes are sparkling clean and she exclaims that the lady seems to have changed her brand of detergent.
Her husband gently says, “I washed our window dear.”