Please see image of Barrack and Michelle Obama, who seem to be saluting backwards. You will note that pin on lapel, wedding rings, and buttons on his jacket all appear in line with the picture not being photoshopped.
Back in 2002, a widely-circulated photograph showed the then-current Senate majority leader Tom Daschle of South Dakota, saluting the U.S. flag with the wrong hand (i.e., placing his left hand, rather than his right hand, over his heart). That the picture was fabricated by simply flipping an image of Daschle was obvious from some simple contextual clues, such as buttons appearing on the wrong side of his suit coat and the lack of a wedding ring on his hand.
President and First Lady shown above: Barack Obama’s suit coat buttons on the correct side, and both the Obamas appear to be sporting wedding bands on their left hands. However, the effort still wasn’t quite good enough, as some obvious details still give this one away as a fabricated image: the Marine in the background (behind President Obama’s elbow) is bearing decorations on the wrong side of his chest, and both the part in the First Lady’s hair and the cutout in the neckline of her dress are on the opposite sides from where they should be, as can be observed in an unmanipulated photograph of the same scene which shows the Obamas with hands (and other details) in proper placement: