Whether you are hitting or looping, you should normally line up your shoulders when you backswing on the forehand so that the shoulders roughly aim in the direction you are hitting towards. This maximizes your hitting zone and allows you to stroke naturally through the ball. If you don’t rotate the shoulders back enough, you’ll have an abbreviated stroke, costing you control and power. (The reverse is less often a problem, but if you do rotate the shoulders back too much, then the stroke becomes too long and cumbersome to control, as well as taking too long in a fast rally.)
So a top priority in developing the forehand is proper shoulder rotation. But once the shot is developed and the shoulder rotation natural, you can use this very shoulder rotation to deceive an opponent.