Okay so we gotta talk about the other Scooby Doo plot of the episode.
There's this place called the Whistling Cave, where people hear it's haunted with the voices of the dead, and anyone who goes there comes down sick with a mysterious ailment, which is used as an excuse to keep out tourists.
This all turns out to be the Centipede Undead hanging out in a cave for some reason just poisoning random humans?
I think he's trying to drive away tourists so he can prospect for gold. :P