Refund 100% if there was really a smoke smell. One of my first guests ( a lady) complained about a smoke smell in the apartment. It was a shock-there is no one living 3 floors below and every apartment has it's own chimney in every room. Now the chimneys are used for ventilation.
She didn't cancel and didn't mention this in the review, but she sent me a message, that there was a cigarettes smell early in the morning.
What was the case...the neighbor above me is a smoker. Because his wife forbids him to smoke at home, early in the morning, he is going in the attic, above his apartment, and smokes there, while drinking his coffee. That's where the smoke comes from. The problem was solved very simple - with a back draft damper. Without this simple thing, when he turns on his fan, the smoke is seeping in my bathroom.