Generally, MB doesn't recommend turning rotors. It's usually justs as easy and cheap to replace MB rotors if they are warped or worn below minimum thickness.

Sometimes rotors can be warped by over tightening the wheel mounting bolts. That's why I always torque the bolts after someone has used an impact wrench to mount wheels on my car.

It's less likely with a Mercedes than some other brands but I suppose the rotors could be warped. A Cadillac dealer did it to my brother-in-law's DeVille.