I once cleared a table at a foodcourt of dirty dishes that a family of strangers had left behind just as they got up to leave.

"Not shy," I said not shyly. They were careful not to look at or listen to me as I returned their tray so that my friend and I could use the table. They may be afflicted by the fascinating forms of voluntary blindness and deafness that arise only when spoken to by cleaners, waiters and one sucker who cleaned up after them.