What I'm really saying is that I try to be as fair as possible and I don't intentionally cheat. If you need to cheat to win, you don't deserve to win. And tennis is the prime sport to cheat in.
Agreed. My point is that there is a margin of error to what you see, and there are a lot of factors that play into it. Place 10 balls close to and touching the baseline, and then have a friend standing on the opposite baseline guess whether the balls are on, long, or short of the baseline. And those balls are stationary!