I've never been to such an event, let alone tried to organize one, but I've socially known various people who've done them (kink but not CNC, to my knowledge) and a few sex workers who did kink professionally, and my guess is that alcohol just would not be allowed. You don't do Jägerbombs before trying a climbing wall, and you don't bring a substance that impairs judgment and worsens coordination to your sex party, for goodness' sake.