Lots of times Windows will braodcast the name of the last computer you connected to if it can't find anything, it's a known thing it does.

So while you may see those names, it could be that it's just their machines broadcasting and you couldn't connect anyways.

There's one person here you can always tell is in the office and which hotel he last stayed at for that reason.

From one story:

Laptops powered by Windows XP or Windows 2000 with built-in wireless capabilities (these includes most laptops on the market today) are configured so that when the user opens up the machine or turns it on, Windows looks for any available wireless connections. If the laptop cannot link up to a wireless network, it creates what's known as an ad-hoc "link local address," a supposed "private network" that assigns the wireless card a network address of 169.254.x.x (the Xs represent a random number between 1 and 254). Microsoft designed this portion of Windows so that the address becomes associated with the name or "SSID" of the last wireless network from which the user obtained a real Internet address. The laptop then broadcasts the name of that network out to other computers within a short range of the machine (which may vary depending a number of things, including the quality of the laptop's embedded network card and things that may obstruct the signal, like walls, e.g.).



If your firewall is enabled, nobody should be able to connect, no matter what you broadcast.