Are eliminated "Vulture Sam" and "Herb Hunter" triggered by "Ghost Town"?
Yes, according to a dodge city faq from the developer. It should be noted that when ghost town is in play players who have been eliminated are still considered eliminated and not part of the game when it is not their turn. If a player had been previously eliminated any abilities their character had will not activate unless it is their turn.

FAQ


  Q15. How the ability of Greg Digger and Herb Hunter must be applied when a ghost leaves play due to the Ghost Town?
  A. Each time a ghost leaves play, Greg Digger regains 2 life points while Herb Hunter draws 2 cards from the deck.


It should be noted that when ghost town is in play players who have been eliminated are still considered eliminated and not part of the game when it is not their turn. If a player had been previously eliminated any abilities their character had will not activate unless it is their turn.