At a recent installment of “Cocktail Wars,’’ a bartending competition on the Boston nightlife circuit, hotel worker Melissa Godfrey glanced around the room and noted how many people she knew from union organizing work. Over there, a young woman who works at the W Boston. Up there, a bartender from KO Prime, the swank steakhouse at Nine Zero.

“Most of the people in the room were union,’’ she said.