Lots of people are alcoholics, and normally they hide it well. No one is perfect at hiding even if they normally pull it off.
I knew a guy who was a raging alcoholic. Held a job, was good at it, went to social events, etc. one day his liver just ruptured and he died sitting in his chair at home with a bottle of Vodka sitting right beside him. His kid found him after school one day.
Maybe we should give her the benefit of doubt. I got pulled over once a long time ago and the policeman ask me why I was following a car so close and I had a bad headache and told him so. Out of the car I go to take the test...ummm passed it with flying colors. Who knew I could do all those things? In the end, he said "you're not drunk and I said no but I kind of wish I was right now after all that!" He was nice and just doing his job.