Air conditioning was broken on a hot weekend. I left early and stayed elsewhere. Still 5 stars. Here's why:
Stuff happens. Period. What matters is how we react. Her reaction was to apologize, try to figure out how to make it right, find a professional to stop by and try to fix it that night (which I'm sure is no easy feat), and give me a full refund despite the fact that I'd already spent 1½ days there, part of what she refunded was AirBnB's cut, and I hadn't asked for it!
The house was otherwise great, btw.