Greetings from Chicago tonight, which has reached 93% humidity tonight and had at least seven "every half century" superheating events in the past two years.
When I called Amazon Logistics, one of their managers informed me that they had closed their shipping centers in Chicago, New York, Philadelphia and Detroit due to the events.
My basement floor is wet from condensation. There is a stream of water coming from the two exposed/uninsulated control valves from the main water intake. Plaster is falling from the condensation around exposed beams in the basement and other areas-- who knows what's happening in unexposed areas.
It's going to take a hell of a lot of work to save the buildings in my neighborhood here under such conditions. It's going to take a hell of a lot of work to save our cities and our planet.
No one should be using a dryer in Santa Fe in the summer. It's inappropriate. It must stop.
In your circumstances, I would have asked your guest if they planned to use the dryer, and presented the option of air drying.
If "no" or "I'll air dry," no problem.
As there evidently is a problem, I'd offer 5-10% discount to compensate, proactively.
In the future, alter your listing to strongly and politely suggest air drying during low humidity periods, or impose it by fiat.
The kids often seem to deal better with imposition by fiat, than ambiguity and lack of clarity.
Good luck and happy hosting.