Foreign adversaries buying ninja costumes in 3...2...1...

from here and here

It seems to me that if you're part of an elite military force you probably should be skilled enough to deal with a lone kook with sword and a costume. Otherwise your enemies abroad are going to get ideas.         

That's what makes it work

from here (image source)

The more specific it is to the environment, the better it does at concealing you, as these two carpet cosplayers demonstrated at DragonCon some time ago.