I visited a few girls at sauna place (P1/P2/P3) and hotel recently, most of them had bad breath, likely from lunch or morning wake-up, which killed the vibe, no matter how gorgeous and hot they are. that odor ruins the whole thing. How would you deal this kind of situation and tell the girl to have a mint?

I would casually bring it up during the shower together — “Do you have mouthwash we can use? I had a spicy lunch” — you can make it about you. I don’t see the girl declining if you offer her the cup after you use it. (If she does, she’s dirty lol)

You can also mention it to the agent ahead of time — “I’m sensitive to mouth odor. Can you tell the girl to brush her teeth before I arrive?” — totally reasonable request.

If there’s no mouthwash in the shower, you can bring it up before bed — take a piece of gum or mint for yourself, then offer it to the girl. “Have you tried these mints? They’re really good and special to Hong Kong.”

If there’s no mouthwash and she refuses your gum/mint, you can just straight up ask the girl — “Hey, I really want to enjoy this moment with you and think if we freshened up together, it’d make everything better for the both of us. Do you have mouthwash or mints we can use?” — just remember that it’s your time and money, so don’t settle for a mediocre experience even if it’s a little awkward to ask.