Removing Black Paint???

I was looking at my car thismornig and notice straight down under the liscense plate on the bumper is what looks like some black paint. It looks like it was from a spray can because it has the spots of paint. I tried to clean it off but it wouldnt come off. What do you guys suggest to take this off. I thought about paint thinner but that would ruin my bumper also.

Mineral spirit possibly?

Are you sure it's not road tar? Try some bug&tar remover to make sure....