This is because the reflection you see every day in the mirror is the one you perceive to be original and hence a better-looking version of yourself. So, when you look at a photo of yourself, your face seems to be the wrong way as it is reversed than how you are used to seeing it.
What Sells Best On Shutterstock?
Some types of photos that sell best are Portrait Photography, Food Photography, Landscapes (usually with people) and fine art photography (artsy).