Tell him to shut his mouth when he chews, I had this very same conversation with a mouth breather leftie werido a few months back. I could smell this guys breath from 100' away in the office.
"Beanie Baby, I don't want to be a prick here, OK? I'm telling you this as someone that's impartial and wanting civility and would rather not be in this position.
My guy, you're a mouth breather, OK. Its quite normal, however coupled with the fact you have halitosis and or gingivitis, its something were going to need you to work on.
Please do not feel attacked (little B!t©h, you 100% should), until that's under control I'm asking you to please chew your gum lips tight and keep your meals in the lunch room."
No questions, no comments... Güd