My AW still sneaks, even though we know, and she knows we know. She's gotten pretty good at it, too. I don't follow her around, but she manages to spike her Dr. Pepper without me seeing or hearing it. (I know it's there because I can smell it, and she becomes obviously intoxicated as the afternoon progresses).
Just my opinion, but if someone is going to great lengths to hide it, that's probably a red flag.
Best of luck, and keep posting.