Okay this isnt much of an exploit but it can help you if u r ganking someone for example
Okay so u wannabeat this ally/horde into the ground, they may off pissed u off so ur sitting around a while untill they respawn if u type /inv "there name here" it will say cannot find "player name " if they have logged off. Or if they are just waiting untill u go it will say that they are unfriendly. This isnt much but it saves u from sitting there untill u relise they are not gonna respawn