A man fires a gun several times at the side of a barn and then draws a circle around a cluster of most of the bullet holes. Drawing a target retrospectively like this doesn't prove the shooting skills of the gunman – no one would consider him a sharpshooter if they knew what he'd done. When the equivalent of this happens in other circumstances we call it the Texas sharpshooter fallacy. As with many fallacies, it may not appear fallacious at first inspection.