I'll admit 9-0 is even past where I'd let up. When I say let up I mean take slappers from just inside the blue line, maybe a few bad angle shots or long range one timers from the point.
To me, no one gains from an asswhooping >9 goals or even 8 goals for that matter. True it is up to the player to stop the pounding but when it's that grizzly, I think a little bit of subtle mercy is called for.
Unless it's someone I can't stand like Carse, then bets are all off