Charging at a strangers house

We spent the last week in an alpine Chalet and had to leave the car in a public parking halfway down the mountain. Upon arrival, the battery was down to 20% SOC. I read that leaving it below 20% or above 80% for extended periods of time was not too healthy. So I asked at a house next to the parking, if I could plug in the car for a while. They seemed friendly and agreed immediately. I told the man that I would need about 40kWh, and asked how much the electricity costs. He said he had no clue and I would have to know.
When I came to pick up the car, I gave him about twice as much as the electricity would cost at the most expensive rate known to me, and about three times as much as I pay at home. That was when he started complaining. He said when he goes to the gas pump with his ICE car, he wouldn’t get a lot of gas for this price. And if he knew that I was going to pay so little, he wouldn’t let me charge. Same for me, if I knew he would be discontent, I would rather drive 20 minutes to the next Supercharger, get free electricity, and still be welcome.
I never paid so much for a charge as I gave him. Usually if the electricity is too expensive at a public charging station, I just drive on to find something reasonable. But I paid him more than I usually would, because I wanted it to be a good experience for him.
I read about mostly good experiences when asking strangers for a plug. But after this incident, I will think twice next time.
What were your experiences with charging at a stranger’s house?