We were doing a function at a hotel in Manhattan on a sunday a few weeks ago. There are normally no open wireless networks there, it's not really a residential area. I found one at full strength. Apparently, guests set up access points on their wired room connection, so the people they are traveling with won't have to do it. The hotel actually goes looking for them when they see excessive traffic on a port.

I'll always search before paying, and most cases find one or many. I found over two dozen open networks in one hotel room, none in the hotel, and most of them did not so any mac flitering, they were wide open.