Up until recent times, I think most people accepted photographs unquestioningly as depicting something that really happened. Unless it was outrageously altered. The introduction of Photoshop changed all that - despite the fact that people have been modifying pictures almost since photography's inception. There is a famous photo of several people standing with Josef Stalin which was "re-imagined" over the years as Stalin had them eliminated one by one.
Almost any professional photograph you see has been altered in some way. So the question is not "if" but, rather, "How much manipulation is acceptable?"
I read a lot of photography magazines where photographers claim they have only adjusted a picture to depict the scene as it appeared when they took the image. Well, guess what? Eyes can be fooled and, for that matter, so can memories. Even those of a photographer. That is a proven fact. That beautiful orange you saw in the sunset may not even be close.
The original unretouched photo straight out of the camera
After opening in Adobe Lightroom and making adjustments to color, tone, etc.
After opening in Photoshop and using it's capabilities as well as a plug-in to "polish" further