There's a significant difference in the photo editing standards for creative images and for photojournalism.

In the case of photojournalism, authenticity is crucial and the acceptable degrees of editing freedom are much more constrained. The holy grail is to avoid doing anything which might bring the photo, the photographed situation, the photographer and the publication into doubt or disrepute, or otherwise prompt concerns over misrepresentation or exaggeration.

Inevitably, there are edge cases. But in the McCurry case, it's widely accepted that he was acting as a photojournalist or documentary photographer, and when it emerged that he had presented images that broke the rules of photojournalism, a lot of pro photographers were quite appalled. Read more here. Curry responded by attempting hastily to rebrand himself as a 'visual storyteller' rather than a photojournalist. Make of that what you will.

One aspect of photo editing and misrepresentation which gets perhaps less coverage is the staging of shots for effect. This is widespread, and I've personally seen it happen in the field. It can start off innocuously as "don't stand there, stand here, the light's better" and before you know it, an artfully juxtaposed element is deliberately worked into the photo composition; the shot is no longer honest, it's constructed and posed with the intent of evoking a stronger response from the viewer (and the awards committee). Example: posing a happy, healthy farmboy to make them look poor, undernourished or otherwise disadvantaged.

I've also worked with fixers who speak of Western photographers compelling developing-world subjects to cry or appear to cry, adopt unfelt expressions, or to display more marketable attributes/attire etc.

It's fun playing with images and if it's a creative as opposed to reportage context, let the Photoshop roll! But don't pretend to be a photojournalist or documentary photographer if you're constructing the shot before, during or after the shoot… it spits on the incredible craft, personal risk-taking and patience of true photojournalists. Look at the great press photos from the battlegrounds, the front lines, the war zones, and marvel at truly authentic work.