I had an unpleasant "zinging" noise that seemed to be associated with the first fret on my Taylor 12-string. Long story short, the luthier found such damage to that fret that he had to replace it. The guitar was only 3 years old when I bought it, so that's damage done in a hurry.
He worked out what must have happened. It used to be common practice to tune 12-strings down a half-step or two, and compensate with a capo. It looks as though the previous owner had done that, tightened the capo right up, and left it on. The resultant grooves in the fret made you wonder how it was playable at all.
So, friends, my advice: don't do that.