IMHO wether the bluing method is basic (hot) / acidic (cold) the problem is the same should you have the misfortune of getting either between the ribs or any other hard to get at area. The one advantage in the cold method is you can use something "mild" like a baking soda solution to neutralize the effects of the acid without ruining the bluing. Water is about the only solvent that will dissolve either the basic/acidic "salts", just using an "oil" without a thorough water flushing does nothing to remove the "salts" - they are only "covered up" and eventually the problem reappears as the oil evaporates, it is somewhat difficult to kept some areas well oiled all the time. Don't forget barrels get fairly hot and it wouldn't take that long for all the oil to be gone and back to square one. I would suspect that's what happened in this case someone did that bluing - oiled the H out of it but did not flush out the "salts". ---John Can.
