I can smell breath that far. I have an insane sense of smell though. That's why I'm always asking other people if they can smell what I smell. The most common odor people also notice but aren't completely aware of how or why, is the poopy/mothy smell of Vaped juice. I work in a kitchen and a few of my servers vape. As soon as they open the front door I can smell shit. They can be standing 20 feet from me talking and I can smell the poop stench floating my way. It does wear off a little over time but not much. The thing with water is if you stay hydrated your mouth hole doesn't stink. My point is that hydration does nothing to battle the vape stench. I don't think biotene would even battle it. If you used mouth wash it would smell like a mint turd. You can deny it all you want. But people can smell you. They may not know it's you, but they can.