This particular shot was a medium close up, meaning that the flash was very near the faces of the boys.
There is large contrast between the white skin tone of the boys and the dark background, this makes the boys look very pale and shows up every blemish.
Using a software off the internet I have decided to airbrush the boys skin by adding a little colour to their faces/necks, and then covering any blemishes, this allows the photo to look more professional and well edited.