What We Remember About Scooby-Doo:

Four teenagers and their trusty dog gallop across the country in their
purple and green van solving all sorts of mysteries and in the process
meet all kinds of interesting people.

The Truth About Scooby-Doo:  

Four high-school dropouts and their sentient dog ride aimlessly around
the country in their psychedelic love machine selling drugs and
occasionally removing some old guy's mask to solve a mystery.
 
The Evidence: 

Shaggy - Not only is he a precursor to grunge with his sloppy dress and
facial hair, but he's obviously a burner (one who smokes marijuana). Why
else would he be constantly hungry? Shaggy can make a six foot hoagie
and swallow it whole. 

Scooby - While dogs do not generally smoke, Scooby gets his high from
Scooby-Snacks, which are in fact hash brownies. Whenever Scooby (or
Shaggy for that matter) eats a Scooby-Snack, he goes ape!   It blows his
mind and he does whatever he's told, simply because he's so lit! Scooby
also has a ravenous appetite. 

While the other characters do not actively take part in this
stoner-fest, they certainly condone the selling of it because it  helps
support their jaunts across the country (and the world - didn't  they
drive to China once??).  These other characters do have their own
peculiarities, though...
 
Though Fred and Daphne are always splintering off from the group to
solve the case by themselves, it's no real mystery what they're really
doing.  They're getting busy in the back of the Mystery Machine.  Daphne
with her pretty pink outfits and Fred with his GQ look are constantly
bumping uglies.  Fred, of course, is pumped up on steroids.  One thing
that remains a mystery is why he always wore that stupid scarf around
his neck...

And what about Velma?  Everyone's least favorite of the cast fooled no
one.  She was a lesbian.  But, as it turned out in the later episodes,
she was also into bestiality.  Where else could Scrappy-Doo have come
from?  Scrappy, who was a dog and yet spoke perfect English, was
obviously the prodigy of Velma and Scooby.  So the kids spent their
teenage years driving around the world, slangin' dope, shooting
steroids, eating hash brownies, having sex with their dog, and all the
while looking for the perfect `hit'.

And you wondered why your parents didn't want you to watch Saturday
morning cartoons...