Here you can see an animation of the original and the final result of the History Brush.

Also note that if you were to set the Bur to a higher radius in the first step, you could rid the photo of larger blemishes as well. You can also use it to reduce wrinkles. It won't really get rid of them, but it will lighten them nicely.

This same technique was used to Restore a 1970's Photo.

Here you can see an animation of the original and the final result of the History Brush.

Also note that if you were to set the Bur to a higher radius in the first step, you could rid the photo of larger blemishes as well. You can also use it to reduce wrinkles. It won't really get rid of them, but it will lighten them nicely.

This same technique was used to Restore a 1970's Photo.