When is it beneficial, ethical, or appropriate to digitally alter photographic portraits? When do you think it is inappropriate or ethically wrong?

I wish I were photography came naturally to me and I every picture I took always looked amazing. However, my photos don't always have the correct lighting or exposure and basically don't look as good as I had imagined. So, in my opinion, photos can be digitally altered if it is trying to get a different effect that the lens originally used couldn't do. I also think that most of the time the raw/original photo looks cooler and has more to it than meets the eye. Now, portraits are a different thing. I would like to say that I think that portraits should not be digitally altered because it is how the person actually looks. However, for my senior pictures I liked the digitally altered images, plus if I don't like a photo that I'm in because of my skin or something, I would like to go in and change it.
Sometimes, the way the skin or the portrait is displayed holds the entire meaning of the photo. So, then it would inappropriate to change.