To most, Idaho is a cheaper state than where they are coming from, and that is what appeals most to them, but maybe Idaho isn't the right state for them to live in.
What would you do if someone told you that you had a spider in your beard or hair? What if you were the person that saw the spider, would you tell the person?
To roughly paraphrase the opening to the action role-playing game Bound By Flame, every undead monster you kill is just one fewer monster, while every living soldier they kill swells their ranks further.