The way we read text influences the way our eyes scan an image. We usually start at the top left, then go to the top right, then the lower left quadrant and finally the lower right. However, it's wrong to oversimplify what this means -- other factors influence what the eye sees first: compositional elements, bright spots, and the human form can draw the eye no matter where they are located.
Moreover, location affects how we read motion and intention; it doesn't necessarily connote importance. Look at Venus and Adonis by Rubens. The top image is the original one, the bottom one is the flipped image. Notice how Venus and the putto are more effective in the top image: the fact that they're pulling in the same direction we're reading gives their efforts more strength. In the bottom image, Adonis is going in the direction we're reading, and he seems a lot more determined and likely to succeed in tearing himself away because of it. The sky and the pastoral patch on the right feels like a more enticing destination.
Usually, when the masters have painted firing lines they've put the victim on the left and the shooters on the right. Below is Goya's Third of May and Manet's Execution of Maximilian (click to enlarge.) The original images are on the left, the flipped images are on the right.
The firing squads seem stronger when they are flipped onto the left, but the paintings have less tension. The victims seem more hapless when they are on the right, but also less noble and less consequential. Talk shows almost always have the host on the right. Flipping an image of Tim Russert with Peter Pace, you can see why. The setting seems less fair and less congenial.