Now, this could be due to crappy code. I was just messing about. But the strangest thing happend:
I destroyed some rooms from a server-extension using the _server.destroyRoom() function.
The rooms where successfuly deleted (they did not show up in the admin tool...)
Now, I had the server check for the existence of these room (if they did not exists, the server would create them). But the server found all these rooms with getRoomByName(); Even though they did not show up in the admin tool under the zone dropdown.
I could even read the roomVariables from this room...