They will have flash rust due to moisture, if they are thick enough, driving slowly, after a few miles of light braking will clean them of the rust.
Bad rotors
No just the bad one.
You either have a bad brake caliper or the brake hose is bad.
could be bad rotors, or brake pads wearing unevenly, which would result in bad rotors.
bad brake rotors or alignment shocks struts
have your brake rotors turned on a lathe, or replace them with new ones.
NO. The rotors will rust overnight if the conditions are right. The rust will be removed the first time the brakes are applied. Yes if the rust has pitted them. Just have them turned on a brake lathe.
A pulsation when braking, and a loud screeching noise(pads also gone).
You possibly have warped brake rotors on the front. Or Bad Wheel Bearings.
This is not much information, but I'll give it a try. If the front brake rotors have too much run-out, "wider in some spots than others" then the rotors need refaced or replaced. If the problem is in the rear brakes, the brake drums are out-of-round and need resurfaced. If you feel the tremble in the brake pedal when you brake, then the problem is certainly in the brake system. ------------ He is correct...the rotors are probably warped. Replace the rotors if they are warped that bad. You can get them turned but they are going to be thinner than new rotors and whatever caused them to warp last time will happen faster. (heavy braking and riding your foot on the brake can cause the rotors to warp)
You jack up and block the car. Remove wheel, remove brake caliper. Rotor is now free.
You have warped rotors. Have them turned at machine shop or replace them. Also replace the brake pads.