If you treat something, without previous discussion, as a "problem" and the client doesn't see it as a problem, you have just insulted the client by saying they need to be "fixed." This can put you in a bad spot (and rightly so).
Making the issue "milder" by doing things you could have done in camera (getting rid of shadows and highlights which emphasize the issue) is fine because that "issue" could appear that way in a photo is one thing. Replacing the hair with skin texture is a clear "fake." If the client has agreed to it, it is an excellent move. If not, it's a problem.