Retouching eyes and teeth
A common photographic challenge is poor lighting. When lighting is dim or not color-balanced, teeth that have a yellowish shade can appear very yellow. This is more noticeable in a photo afterwards than it is at the time, since the human eye tends to disregard such things in real situations but notices them on pictures.
Another lighting challenge is when lighting comes from high overhead. This often creates unpleasant shadows under the eyes, creating the “bags under the eyes” look that we all wish to avoid.
A little Photoshopping makes a big difference. Take a look at the before and after pictures.