I played a match recently where my opponent called every shot on the line out. He even called shots a few inches inside of the line out. I realized during the first set (that I won) that this was his strategy to try and hook me on the calls and also to upset me by a pattern of disrespectful things. (After the points are over on my serve, not hitting me the balls back but spraying them all over the court, quickly serving when I'm not in position etc...)
I don't know if these things worked on other people but I picked up my game and bageled him the second set. I'd love a rematch so I could double bagel him.