Most people I know don't care about this. They drink to the point where their own health don't interest them anymore. I visit a lot of festivals in germany where it can get pretty cold at night. But the later and colder it gets the less do the people wear.
On the next day they feel bad and caught a cold or worse! Of course I know the warming effect of alcohol by myself. I try to drink slowly so the effect is not too strong. Most times it works!
At some village fairs, where the people are drinking a lot, you even see them sweating, only from drinking alcohol! That can't be healthy ;-)
I hope a lot of people will read your post. Having a warm sweater in your car or bag is always a good idea!