Except for rare instances it`s a financhial loss. There may be other reasons to reblue though. Long ago I was in a terrible motorcycle accident. As I was single my best friend and his wife took me in and nursed me a few weeks. I gave bill a nice smith 1917. Sometime later we were deer hunting in the high sierras and I met another guy that I knew and we all camped together. We started talking guns and bill went to his camper and got the 1917 I had gave him to show off.
He pulled it out of a leather case that had once been a sample bag or demo kit when he had sold amway products years before. The gun was completely frosted with rust! It must have been from some chemicals that had been in the case. My friend had a ffl and was a S&W guy. He said let me send this to the factory for you. This was so long ago that I think the reblue was $16s! The gun came back with the prettiest deep ink looking blue I had seen! Of course it was far more spetacular than the original 1917 finish but bill was pleased.