brake sound

[djembeing]

i recently had the driver-side ball joints replaced on my 97 explorer xlt.
The mechanic told me that there would be a swishing sound when I brake (he said something about rust). I took the wheel off to inspect and make sure we were still safe and to try to find the sound.
It looks like there is a rough spot on the rotor. I know it wasn't there before because braking was smooth and silent. Now, I think I understand what he was saying. That he was using some kind of rust remover to get the old ball joints loose and got some onto the rotor. I think whatever product he was using must have eaten into the surface of the rotor causing it to make this sound when I brake.
My question is, how concerned should I be, should I let the rough spot wear down itself or get the rotor turned. (could not get caliper mount bolts out, so if it'll wear itself down safely that'd be nice)(brake pads are good)
It's just kind of an annoying sound and I think people hear it and think I don't take car of my car.
thanks in advance.
dave

also, are there certain products that one should avoid getting on the rotor or other parts.

 

[drdoom]

You might try re-installing the pads, doing a good cleaning of the contact surfaces, and a careful application of a quality brake grease.