In my case, I think AH simply doesn't want to admit they've been drinking but for some reason they think they can convince you of it despite all evidence to the contrary.
Today is our 40th wedding anniversary. We planned on going out to a nice restaurant for brunch. I figured that it's brunch--how drunk could he be at 9:00am. How naive of me.
He was so excited about our anniversary he was awake at 3am and pretty much drank from 3am until 9am. He was wasted. So I told him that perhaps we should forget brunch and do dinner, as long as he doesn't drink anymore, and he actually protested that he hadn't been drinking. He was drooling on himself, and slurring and having trouble dressing, but nooo he wasn't drinking!
He implicitly admitted he had been drinking by agreeing to skip brunch. We wound up going out for dinner early; he had sobered up enough. We were home by 7:00 and he's already in bed sleeping. Ahhh, sweet peace!