If you use the right paints, they can be removed completely, with no damage to the gun. I usually use Testors, but I have used Krylon (not Fusion), and it seems to come off just as well.
These were painted for over 25 years, and the Mossberg still is.
I stripped the 1100 a couple of years back, and restocked it. As you can see, the parts that were painted, no longer are...
As far as spooking game, Ive found they come in a lot closer, and especially when bird hunting in the open, when Im all cammied up and my gun is painted, versus unpainted.
They do notice the movement, but the difference of the unpainted gun moving is much more noticeable and eye attracting, than one that isnt.
Multicam is a very easy pattern to do, and it does work great.
Same gun without the background...