In over 10 years of using Flitz exclusively on my blued guns, I have never had a problem like the one you described. I suppose if somebody rubs the snot out of a gun, they can remove blueing, but it would take quite an effort. The one thing I have found is that Flitz can remove cold blue products. If the area in question had been touched up, that might account for the "fog". Other than that, I have no idea how you could have had a problem. As far as Flitz being abrasive, so are dry cloths and holsters. I have used it on at least 35 or 40 guns through the years and have had no problems at all.