I think it depends on what you are trying to achieve from the photo and what the subject matter is.
I mainly shoot wildlife/nature and editing a photo is one thing, manipulation is another.
For instance, I sometimes see photos where a catch-light has been added to an eye of an animal because there wasn't one. This is very different to me grabbing a highlight brush and enhancing a catch-light that is already there.
Another example, if there is something in the photo that is distracting, maybe a clump of grass that is a different colour that pulls the eye away from the main subject then yes, I probably would remove this with content aware in Photoshop. Cheating? Maybe, but that's something that I wouldn't be able to control in the original framing. However, changing the entire background to something else because the photo was shot against a building? Possibly too much. Although acceptable if you are honest about it afterwards.
Adding anything into a shot, then that's something very different and not something I would entertain, unless it was artistic, but then I'd make sure people knew about it.
Personally for me, I think adding an artistic element to photography in post is perfectly acceptable providing you are not trying to mislead and are honest about it.
I was recently was out photographing Short Eared Owls and this shot below was taken into the sunrise, did it look anything like this shot? No, not really but for me, it's adding a little artistic approach to make more of an impact to the viewer. However, I think that most people would realise and accept that to produce this image, it will be processed in post to achieve it. I did, however, take the shot with the intention to create this effect.
Short Eared Owl (Backlit) by
Craig Rogers, on Flickr
In the example of the OP, it's a fine line. If a photo looks a lot better by not actually looking exactly what you remember it looking like different shade of grass for example, as long as you are not trying to heavily mis-lead the viewer, then I'm guessing it's ok within reason.
These are just my thoughts and some may or may not agree, which is why the subject is difficult to say what is right and what is wrong? I guess the answer is neither.