system
Given the following post, respond as if you're commenting on Reddit:
human
[Dresden Files] I currently run a rather popular motel in Chicago and I want to keep the dark creatures of the night out of my building. How can a magical newbie (and human) like me protect my clients from the things that go bump in the night

I only just learned that vampires, wizards, and demons are real. Can I just put a sign on the doors of my motel rooms that say "No magical beings allowed", or would that not establish enough of a threshold?

What can I do to protect myself and my clients?
gpt
Sorry, a motel will never have a sufficient threshold. Not unless someone takes up residence in one of the rooms for years and years. 

Your own room, if you have one, should be fine.

As for protecting your clients, a threshold would not do this. 

A vampire doesn't have to walk in the room to kill them if they really want to. They can get a mortal to do it, or just set the place on fire.

Do *not* put up a sign. It's an insult, and it could be worth your life if the wrong creature read it. You'd only be keeping the polite magical folk away.