IME, it's been the 3am phone calls with crying, bla, bla, bla, and then the sound of snoring. I have a recording of the snoring.
In general, one perceives no discernible 'switch' in the partner for turning off drinking.
Also, I'd be mindful of a person who drinks as in the example and is reticent to give up their keys to the DD.
Also, with women, more bathroom trips than normal.
I've had a fair amount of friends and a few ladies I've loved who were/are alcoholics, some active and some in recovery.
Since I generally date with the intention of finding a marital partner, I would pass on an alcoholic as potential marital material. That doesn't mean I wouldn't love them, rather find them incompatible for a LTR.