I have a friend who always used to clean rental cars she was returning to the rental place, purging them of food wrappers, newspapers, empty bottles and the like. Since this was before rental companies threatened to fine you for leaving a rental car in a state of disarray, I always found it odd.

"We're paying for them to clean the car," I would say to her. "Why do their work for them?"

It made no difference; she just thought it was the right thing to do.

I've always thought of that whenever I hear Larry Summers' axiom, "In the history of the world, no one has ever washed a rented car," quoted by Tom Friedman about a bazillion times.

In fact, I thought, some people do clean their rental cars. They may not take them to a carwash, but the use of the term "wash" is a clever red herring, because while people might not go that far out of their way, the principle at hand is cleaning, and lots of people clearly do clean their rental cars—and that suggests an interesting and irrational kind of economic behavior worth considering.

Apparently I'm not alone in feeling this way, because Tod Lindberg in the Weekly Standard has a piece about this exact issue.

I got to thinking about it the other day when I got back from the carwash with my rented car. Alas, I am quite confident from my subsequent research that I will not go down in history as the first person to wash a rental....

There's a converse that I wish someone would also study, which is why people trash things that, in theory, belong to them. I live near Harlem where, I think it's safe to say, there's not exactly a culture of environmentalism, and I see people throwing their garbage on the street—their street—all the time. Cigarettes, fast food wrappers, Red Bull cans, etc.

If the ostensible theory behind not washing a rental car is that people don't take care of things they don't have an investment in (the case for home ownership, right?), then why do people abuse things in which they do have ownership?

Or perhaps there is a false assumption there.