Unsafe: Most polishes and lead-away cloths. They will take the blue off with some rubbing and right away, respectively. Also: cola and blood can strip blue faster than anything.
Best to pick a single product like CLP or FP-10 and not only use it to clean but to coat everytime you handle the gun. I don't know how the matte blue holds up vs the polished blue, but in general even fingerprints can eat away rust spots on a blue gun in certain climates - and at scary-fast speeds. Keep a oily rag around, give it a few drops when it dries out, and wipe that gun every time you handle it.
Oh, and post some photos.