When a person has been a drinker for years and years, like over 20 years, it can be hard to tell when they are drunk. Not because the signs aren't there but because the signs have become part of how you "normally" see that person.
Several nights ago I had dinner with my in-laws and my BIL #1 was there. He is a drunk - my opinion, I take responsibility for that statement. The first night we were together we had dinner at a restaurant. Did he drink in public? NO, only water. He was rather quiet but still only talked about himself. Our last public dinner with him was disastrous. He came drunk. He ended up sitting near the kids by chance, was overly loud, acted strange, etc. There was a big blow-up on the ride home that night. So am I surprised he only drank water this time? No. He tries to be a good boy. You can tell it's hard on him to restrain himself. This is a challenge to be with family. There are a lot of pressures for him.
The second night we have a dinner at home; it's at my in-laws. This time the eyes are glazed, the voice is loud, the mannerisms are that of a "funny guy" - he tries to be a joke-ster. He gets really close when he talks to you - almost too close - and the alcohol is very strong on his breath. I swear if I lit a match he'd burst into flames right then and there. He corners my son and talks about himself when he was young. My son kindly listens as his uncle is too close and goes on and on about things he doesn't know or care about. I try to run interference. I'll be the ear for the funnyman tonight. It is hard to bite my tongue.
After dinner I am washing dishes and my MIL says to me, "I don't understand him. He always gets goofy when you all are around." I look at her and say, "He's drunk. Can't you tell?" But of course she can't. She's been around him too many times when he's been in this state. And she's his mother. It seems that is a fault with mothers...we want to believe the best of our offspring.