Honey, you can skip this one

My wife is a better person than I am by orders of magnitude. She would always prefer to believe the best of people and be thought overly naive and generous than be thought cynical and mean-spirited. I, on the other hand, couldn't resist mentioning this gem. Here is the scenario:

One unit in our building is owned by a really nice couple and occupied by their daughter, who fulfills none of her responsibilities as a resident. The most conspicuous of these is the weekly washing the common entranceway and stairs, which falls to the resident of her first-floor unit every fifth week.
The head of the tenants' committee has sent reminders to everyone about this to no avail, and I think every single resident managed to slip either this or some other lapse or issue into conversation when her parents showed up for a weekend project to landscape the back yard (though the daughter was a no-show). Their response was always to pass the buck to us and encourage us to teach their daughter about her adult responsibilities.
So the residents get an email this week from the mother, saying that the daughter says the reason she hasn't ever washed the hall or stairs is that she doesn't think it's right for her to wash areas (like the second and third floors) that she doesn't actually walk on herself, but now she says she would be OK with washing from the front door to her unit, i.e. the bit she actually uses.

How to respond to that, I wonder? Any suggestions?