People will just let teenagers go anywhere. Closed museums, abandoned castles, empty fun parks, haunted movie sets. It's all good.
Scooby (and Shaggy) should be exceptionally overweight, fighting diabetes and high blood pressure, or potentially dead from the amount of food eaten in the space of one night.
Some people come up with exceptionally elaborate plans to scare people away in order to obtain family fortunes, escape with money or just plain old fashioned revenge.
The whole thing is a little implausible, but over all we do seem to just stumble on a mystery very easily.
There was a new collar left for Scooby today, the one from the dreams. He seems to really like it at least.