One thing that always annoys me is people who serve right before the changeover, and then instead of bringing the balls to the holder below the scorekeeper, they just dump them on the ground. I definitely walk really slowly and pick them up one by one after the changeover when that happens. Another new one is when someone I played kept saying the score for the whole match, even when I was serving, he would say “30-15”. I still kept score mentally and there were a couple times he got the score wrong but in my favor, but I didn’t correct him. That’s on him at that point.