[DanBC]

The original image is fine. What is gained by faking the sky? Faking the sky, and adding a note to say that the sky has been faked, is fine.

Fixing red-eye is borderline and needs to be done carefully. Someone fixing red-eye and obscuring a coloboma has distorted the image, and distorted truth.

Can you really see no difference in fixing a photographic defect and adding in stuff that was not there?

Obviously it depends a bit on where the image is used, but I'd hope that any publication would list the changes made to a photograph.