This one time I took out my pre-netbook hand-held and brought up it's sniffer in a crowded neighborhood near here. (I.e. A high-density housing area.)
There were 147 VISIBLE WAPs and 23 with "hidden" SSIDs.
58 of the VISIBLE WAPs were
wide open, and more than half of those were completely UNCHANGED from their default, factory settings.
Funniest part was that
6 of the "Hidden" SSID ones were wide open too!
LOL!
(Ya, I was always pretty good finding people when playing Hide-'N-Seek as a kid! )