LOL.
I am totally against any league type of scenario, as i am just not a team player and never will be.
But in pool, your always gonna have the people that honestly don't know, or don't care, or the ones that think that there is nothing wrong with anything they do.
So i can see all view points.
I can see the "it's rude and tasteless" view, on how people shouldn't be that inconsiderate and should have some tact when dealing with the opponents on another team.
I can also see the "cheering for their teammate" view, as the game might have been crucial, and they might not have meant any offense.
All things aside, this is pool, and there unfortunately is NO standard whatsoever.
If the people who find it offensive, wanted to stop the behavior, they could simply try and change the rules to incorporate this as a sportsmanship issue, but your still going to have people that blur the lines between "was it when he scratched, or was it for their teammate"
And since this is involving pool players, that means that the issue will NEVER be resolved.
As for me, if they were a respectful team to play, and had behaved properly with no comments under their breath and ignoramus type statements, i might have said "tough break"
But you can be sure that if somewhere in the match that they pissed me off, when i saw that cue ball rolling towards the hole, i might have yelled out ONE TIME!!!!!!! and then done an endzone dance and bought the room a round of drinks cause i was SO happy that the idiot scratched.