I agree totaly with you on this Marc. Trying to pass off a fake rainbow as the real thing is wrong. A lie is a lie. But there has been times that I have replaced skies or removed items from my pictures without stating so to see if my PS skills were good enough to pull it off. I have seen some pictures here a PR that are times that I thought were almost to amazing to be true, but the photographer insists that it is real. I would never PS a piece of work and claim it as he real thing if it was not, no matter how good at PS I get.
Everyone has their definition of what photography is. or what it should be. I feel Trog makes valid points, adding elements to an image and then trying to pass them off as the real thing is just wrong.
Greg