Succeeding or failing to accomplish something has several possible effects.
The lock on an object usually determines whether you will fail or not.
You fail to use a THING when you cannot pick it up.
You fail to use a PLAYER when you cannot page them.
You fail to use an EXIT when you cannot go through it.
(exits that costs more than you can afford, display their @FAIL message).
(unlinked exits can not be used and do not display their @FAIL message ).
Failure to "use" a room merely alters what the player sees while
looking at the room. If they can't use the room, they see the room's
description and @fail message; other players see the @ofail message
everytime the player 'look's. If the player CAN use the room, then
they see the description and @success messages, while others see
the @osuccess message as the player types "look".