I always thought the
GKs seemed a bit silly. Rather than trying to hide their existence, why don't they just pretend to be someone else?
Hell, they could just paint their armor black. Everyone would be like, oh its the Deathwatch. Or just paint their armor to look like random chapters every time. Its just paint. One week they're ultramarines, next week they're blood angels.
Meh. Its just a waste of their time. Not to mention I doubt really anyone even cares that much. Its a big universe and who has time to worry about some random space marines you saw shooting xenos and chaos.