Using the healing tools in Photoshop
This is a technique easily applicable
in Photoshop's healing tool: how to “repair”
pictures (removing disturbing elements). First select a reference in
the picture
by alt-clicking on a pixel. Select brush size and type (replace, add,
…) and
paint on the picture. It is amazing how efficient that tool is. You can
really
remove disturbing elements from pictures. This can be used too to
remove dust
spots on the picture (due to dust on the sensor).