I had a problem with hard tannish-grey gunk surrounding the base of the faucet on the bathroom sink. I think it was stuff (plumbers putty?) that the handyman used when installing that had seeped out and hardened. It made a ring an eighth of an inch wide. Scrubbing didn't touch it--neither did the lime remover and I was afraid of damaging the finish as I did in the tub. Vinegar worked s l o w ly with a lot of hard scrubbing.

I don't know what made me try it, but I sprayed it with some lemon PAM that was in the kitchen, let it sit for a few minutes, then scrubbed with the vinegar wet rag. It came right off! and the finish is intact--YAY!