Why do you use spell-check?
To fix spelling mistakes that would otherwise make you look unprofessional.
Why retouch a photograph?
To fix mistakes in a picture that would otherwise make you look unprofessional.
There are many possible photo mistakes: the lighting is weird, something is crooked, a jacket collar is twisted, a face is too shiny, etc. Some of these truly are mistakes because the photographer should have fixed them before taking the photo.
But some things can’t be fixed beforehand by the photographer: facial blemishes, yellow teeth, unfinished construction work, bad weather, scratches on the product packaging, etc.
Retouching a little or a lot
A little retouching might be needed for business portraits. Removing facial blemishes, cleaning up dust and loose hairs on clothing, and brightening teeth and eyes are common tasks. Straightening real estate photos is another typical little job.
But some photos may require a lot of retouching. This can include such things as reshaping an object or even removing the object, removing eyeglass reflections or refraction, fixing poorly positioned eyeglasses, hiding unfinished construction, adding a new background, adding a new floor to a room or a new lawn to a house, and many other changes that a photo might need.
Retouching Business Headshots
Retouching business headshots and group portraits is a very common request. Often the customer just wants blemishes removed and wrinkles minimized. But sometimes more retouching is necessary to fix crooked or loose clothing, change the background or remove something from the photo. Group photos almost always require retouching to fix the inevitable awkward expressions on some of the faces.
Here are some more examples of my photo retouching.
There is a limit to what retouching is possible on any given picture. For example, low-resolution photos and out-of focus images are much more difficult to retouch; patterned clothing is more difficult than solid colours; and, of course, skin textures are always challenging.
If a photographer knows ahead of time that a picture will be retouched, they will (or at least they should) shoot extra pictures that can be used as source photos for the retouching.
Look over your current business photos and headshots and ask yourself if they need to be fixed or polished. Professionally retouched pictures get more attention and make you look more professional.