system
Given the following post, respond as if you're commenting on Reddit:
human
Since the adventures of Scooby Doo and his gang have pretty conclusively proven to us that there's no such thing as ghosts, why do a few periods of their life seem to contradict this?

I remember back when Scooby and some of the gang were tracking down thirteen actual ghosts, or more recently, encountered some actual zombies and cat-creatures.  Just what is the nature of magic in Scooby Doo's universe?  Sometimes logic can be used reliably, "ruling out the impossible", as Sherlock would say, but sometimes it can't.
gpt
Why do you think Shaggy and Scooby would be scared shitless of every disaffected carnival operator in a glow-in-the-dark costume if they didn't have real experience of the supernatural? This also explains why attempting to disguise fairly petty crimes as the activity of ghosts is so incredibly common in their world. In fact, the gang, though skeptical, tend to approach each event they investigate as if it could be supernatural, ruling that out once they find clues that point to a mundane origin. This suggests a setting where supernatural events do occur, but are rare. As the gang picks up a reputation, they eventually start to become more and more involved with higher profile cases involving genuine supernatural powers.