Played a well-respected guy from my area in league setting recently, had my back to him blocking his view of a simple shot into the side, which I hit softly enough that there was no audible double click for him to notice. Later confirmed that no one had noticed anything odd about the shot from any vantage point. Called it immediately and won some respect from a grizzled veteran.
Went on to play the rest of the set at the speed I should play and beat the much more experienced player by a huge deficit. I like to think karma pays, but who knows, it's just the proper thing to do if you respect any competition of skill.