Sometimes you will want to remove stains or residue from adhesive badges or labels on mic bodies. The art: to remove the stain without irreversibly altering or removing the mic’s surface plating.
Here is the general rule when choosing chemicals or mechanical means to remove foreign objects or dried, staining film from mic bodies: start with the lowest impact chemical and work up from there. The ultimate cure, mechanical abrasion, will usually also cause ultimate and irreparable damage to the surfaces they are applied to.
Here is how I usually proceed, in the order from mild to aggressive:
1. VM&P Naphtha - the same stuff luthiers use when they need to remove pickguard adhesive from even the most expensive acoustic guitars: it will not harm the surface of your mic but in many cases will dissolve the adhesive.
2. 100% or 99% Isopropyl Alcohol. Again, in this case it will not affect the nickel-plated surface of your mic.
If that still does not remove the yellow stains, and if you are sure that the letters embossed into the surface are anodized black, rather than painted black, choose:
3. Acetone. It's the most aggressive of chemicals I would use on a mic body. It does not affect or bite into metal, but if the lettering is painted, it will affect or dissolve the paint. If the lettering was black-anodized, acetone will not affect the anodization.
Test the acetone on a section of the lettering that is hidden or not in the center of viewing: put a small amount of acetone on a Q-Tip, and lightly rub it across a lettered area. If the Q-Tip turns black, the acetone dissolved paint. Even with painted letters, you can still use acetone on this mic, if you are very careful: remove the yellow film around lettering, and don't rub the acetone into it.
I would stay away from abrasive cleaning pastes: at minimum they will later the sheen of the affected area and make it brighter, at worst, they will leave scratches that cannot be removed without causing ugly shiny spots, if you try to buffer them out.