A lot of bad players get pissed when you check the rack on them. It's happened to me numerous times in APA 9-ball. They think you're calling them out for dishonesty or that you're an asshole for being too picky. The SL5 and below players know not what they do.
On a kind of amusing side note, I have an SL2 teammate in 9-ball who checks the rack every time she breaks even though she can barely get 4 balls to hit the rail when she breaks. She takes her break very seriously.
When it comes to APA..I think most 9-ball players below SL 9's are beginners. But what do I know..I am just a SL 5..with my head in the sand..its sad when some one can't rack.
There are those's that will loose rack you in a instant..they have no heart..loose rack me an I'll safety them to death..its what makes the game fun..more aiming fluid scotty.