I have an 1861 that is still armory bright and doesn't look like it was ever "cleaned". Just a bit of luck to have escaped the almost inevitable rust.
The idea of making and issuing rifles in "armory bright" was that failure of the soldier to maintain his rifle would be clearly evident to an inspecting officer. Eyewitness reports say the sight of a well-drilled unit, marching in close order with bright muskets and bayonets shining in the sun was truly spectacular. Camoflage was known and practiced in irregular units, but in the regular army it was not only impractical but pointless - you just don't hide a miles long column marching along in formation.
Jim