Nope. Got pictures of the area? Maybe someone can suggest something.
BTW – all of the slumlords that I’ve heard of would NOT fix the area. Epoxying/sanding/matching an enamel color would already be a very non-slumlordy thing to do.
If you have someone that won’t take a unit because of a 1″ x 1″ discoloration on a tile, I’m pretty sure you don’t want them anyway. Imagine them obsessing about tiny things (“the faucet has a little bubble in the chrome”) and calling you about them at 2 am…