There’s many forms of retouching and lot goes in behind the scenes. Minor adjustments may go unnoticed, but they contribute significantly to the final image.
This is probably the most prominent form of retouching and it can be a bit controversial. There’s is more tutorials out there on this editing type than a person could ever watch. Also, there’s hardly a photo retouching application there that doesn’t have it. Done properly, when necessary, it can help the message you want to send. I only offer it on a case by case basis.
Every product has some. I’ll find them. Sample and prototypes have them too. Do they affect the performance of the product. Most probably not. Sometimes they don’t even concern the product. The package may be a bit bent out of shape. We still need perfection.