In the real world, I declined a drink with my colleagues, and my ring which "Never Loses" would not be bested. Yet in the game, I had to use the offer of a drink to achieve my own goals.
As players interacted more with the game's NPCs, the Undead slowly discovered that NPCs were not of low intelligence; on the contrary, they were very smart, could be tempted, and sometimes spilled plenty of information when drunk.
They were virtually just like real people.
While they naturally resisted contact with the Undead, their mouths could still be pried open with the right incentives.
Understanding the preferences of each NPC essential to the core became a must for the Undead, and some even compiled the "NPC Preference Strategy Codex" on forums, gathering and organizing key NPCs' likes to make it easier for the Undead to strategize their approach.
For instance, Miss Miko had a particular fondness for Magic Potion ingredients; shower her with them, and she would smile at you.