There is a good theory to this show I have come up with...and that is this...they were proper potheads...note all the 'Scooby treats'...note how they ALWAYS had the munchies...drove around in a van accusing the local high ranking towns people of crimes...hence the paranoia. Now...I don't think ANYONE but them knew what they were talking about. Didn't you ever wonder when those 'Scooby snacks' were spoken of by Shaggy...what did those taste like? True story...when I was kid I thought, they should TOTALLY make a product called 'Scooby Snacks' and market it. In later years I did indeed go into marketing and if I may...did quite well...yep...it was a calling...but imagine...Scooby Snacks as a kid...that would have been cool ;}
the better question is why does his owner eat dog treats?