I’ve seen, handled and owned probably more than my fair share of original rifles, and for the most part original flintlock guns don’t have the Cloroxed look on the metal surfaces. The touch hole might be a 1/8” in diameter, but that’s just from being shot a lot. Generally, the barrel isn’t pitted to extreme, nor is the lock. A lot of guns will have some pinprick pitting on the breech or the barrels, and some with burning in the pans.
Percussion guns, or flinters that have been converted to percussion, can and sometimes do have a lot of pitting, even to serious eroding on the barrel around the nipple drum area, and on the hammer and lock plate, but this was caused by the fulminate of mercury or whatever the heck it was that was in the percussion cap.
Now, that’s not to say that some old gun left out in the barn for a hundred years or stored in a hot damp closet won’t be all rusted to $#*!, because it probably will be. But guns that were given ‘normal’ care generally look much better. I’d post some pictures, but I’m out on the ship and don’t have any suitable examples on this computer.
John