Alcoholic

Coding: This article contains code which is for experienced users only, and may reveal game secrets

IsAlcoholic as defined in char.dat states whether a character will ignore a food's consumeWisdomLimit so long as that food is a beverage.
This causes alcoholic NPCs to consume potentially dangerous liquids (i.e. ones with negative effects) such as Vodka if they come across them, whereas normally sufficiently smart monsters would ignore them.

Alcoholic characters include:

• All types of Guard
• Ivan

truth material::CanBeEatenByAI(ccharacter* Eater) const
{
  return ((Eater->GetAttribute(WISDOM) < GetConsumeWisdomLimit()
	   || (Eater->IsAlcoholic() && (GetCategoryFlags() & IS_BEVERAGE)))
	  && !GetSpoilLevel() && !Eater->CheckCannibalism(this));
}

Entertainingly, guards are able to sniff out alcohol on your person. If you try to chat with one, he will ask "Do you have something for me?" and prompt you to hand over a bottle of alcoholic liquid on your person.
If you comply he will promptly drink it and become confused.