I don't like the fact that anyone's faction should be known to everyone. Only slavers would be an exception because you have to have a tatoo.
Let's say someone is mining in an unguaded town. If a gang that hates the gang the miner is in, they shouldn't just be able to automatically know what faction that miner is in, and kill him. There should still be some element of mystery.
But, apparently Voland already made a command that's on the wiki that will make you be able to tell what faction a player is it...