Have you ever looked at all the fashion magazines and seen the most gorgeous models on the cover? You never see so much as a little blemish as they have the perfect picture skin and it is a perfect picture. The mystery behind this is it simply comes down to the retouching of the photo.
With various retouching techniques, it's quite easy to remove a little scar or perhaps some minor acne breakout for example. Sometimes it's done just with the makeup before the photos are taken but often it's done after the photo has been done. It's just done with photo shop retouching techniques for example.
It's much easier to do it with the photo in many cases. What happens is that if it's being done manually prior to the photo the makeup might not be just right or maybe looking thick and uneven. With the digital photo retouching it makes it much simpler because if it's not right the first time you can simply keep working on it until you get it the way you want it.
That's the nice thing about owning a digital camera. Now you don't have to have a professional to fix your important pictures. Again, it will be done with the various software's that are available on the Internet.
You are going to have to have the image editing software. Some free ones that are on the net are quite good such as Gimp. If you want something that's far more intense, you probably would be better off with Photoshop.
You may be somewhat limited with Gimp as to what you can do but with Photoshop, there are multiple things that you can do to get the effect that you want. Let's say for your photo shoot pageant retouch you need to smoothen soften the skin or perhaps you need to get rid of a blemish or make the eyebrows fuller it won't be a problem. Then if you need to add some makeup or even tan the skin, a little bit, you can do it as well and you can even remove stray hairs. You can whiten the teeth or you can touch up the shine on the lips for example. As you can see there is virtually no stopping what you can do to alter the looks of the model for the project. Many Photoshop tutorials online will teach you and take you through the various steps of what you can do.
It's important that if you take your photography seriously that you learn all the techniques that are available to you to allow you to be an excellent photographer. There is certainly no problem or reason that touchups are not acceptable. Almost any developing company or photographer would use these methods whenever necessary. The object is to get the picture perfect.