I really like this idea, it will get easier to identify your teammates and it will be easier to spot when a team moves into towns, woods and other areas where they can hide. If you se a guy/gal wearing a bandana around his/her arm you can assume that it's a bigger group and adapt to that. You can also just slap a bandana onto your arm and trick people into thinking that you're a part of a bigger group and that might scare away bandits. It just add another way to do things, if you think it's stupid, don't do it. I know it have been done during military exercises to create two diffrent sides without having to use two diffrent uniforms, it's commonly used by airsofters and paintballers where every uniform in the world is used. The trick is to use it your arm that grips the rifle because when you're aiming, the bandana will behind the rifle and only the guys behind and to your right will see the bandana. Your should have a color that stands out from your uniform because otherwise, what's the point? You should be able to adjust the brightness with the condition of the bandana. A pristine would be bright while a badly damaged would be in a darker tone. In real life you take a brightly colored bandana and smudge it with dirt so it won't stand out to much. From a Swedish soldiers handbook, early 90s. It's used to identify friend from foe in urban terrain.