In fact, many mermen already had misgivings about Vaan's Heavenly Massage. Given the constant moans that escaped the tent, they didn't feel confident that they could keep their mouths shut during their service.
However, the observable benefits of the Heavenly Massage were just too good for the mermen to pass it. As such, they ultimately queued up to try their luck.
Unfortunately, since Vaan did not accept males, the mermen could only give up.
"Perhaps this is for the best," a dispirited merman sighed, saying, "I'll probably die of shame if I made such embarrassing noises and was heard by everyone. I would never be able to go out in public with my head held high again."
"Can't we just set up a sound insulation barrier so that no one outside the tent can hear us?" a wishful merman wondered.