NPCs in my game get annoyed when you waste their time
In my game Table of Fates, Karma is very valuable and heavily influences how a run plays out.
If you keep bothering NPCs without helping them or buying anything, they slowly start getting annoyed with you, causing you to lose Karma.
Your Karma affects how the tavern reacts to you: which NPCs are willing to help, how often events appear, and even how valuable certain offers become during a run.
Edit: I now see the concerns about discouraging interaction and immersion breaking. I appreciate the feedback and will definitely revisit how these interactions work.