Multiplayer cheating is lame.
But I must admit that I've done it.
I once used the Spectator Hack in Counter-Strike (let's you plant/defuse/rescue/shoot etc., but as a ghost so no one can see you). I laughed so hard at one guy trying to rescue the hostage who were always running away that I almost fell of the chair.
Hey, I did it only for 5 minutes
It's not cheating, it's exploring!