It is usually different and I will attempt to explain why. If you went to the service line and hit your service underhanded in a manner consistent with your usual order of business ... absolutely no issue. In fact I am ok with it you have a huge serve, set up to the line to see me standing 10 feet behind the baseline, and at that point you decide ... ok I guess I will hit the underhanded serve. As long as you do not scheme to catch me off guard. Attempting to catch me off guard once the point is started is fine ... However, my issue with the treachery comes when you alter your order of business. I will give you an example. We have a habitual underhanded server in my area. He uses it in the following situation: A ball will be in the in the court when I move forward to clear the ball. I return to my position and as soon as I turn around he has hit the underhanded serve. He has changed his timing, his pace and the manner in which he has hit this shot. It worked once and now when I clear a ball I just raise my racket until I am in position. But he gets very irritated when I do this because he knows the shot can only work if he does not allow me to get set. Now this is an extreme case ... but if you are an underhanded server and alter other parts of your game to set up a situation when no one expects you to start the point ... this is a problem. This is gamesmanship ... this is bush league ..... I don't like it and if I have a choice I wont play with these folks.