Dark And Interesting 'Scooby-Doo' Fan Theories About Scoob Himself

From TVTropes.com:

Every so often, Fred or Velma will ask Scooby to act as a sort of bloodhound and get him to pick up the scent of the petty felon in the mask messing with them; the problem is that they tend to be hazy on the fact that Scooby can't turn his sense of smell on or off like a machine. Like any other of his senses, it's on twenty-four/seven; that means that the costumes can't and don't keep him from knowing who the crook in the suit is. To him, it's just another suit of clothing that the person happens to be wearing; since people know that he can speak English, he thinks that his ability to identify the malefactor du jour is a source of danger to the teenagers that happen to be in his vicinity. He only feigns a belief in monsters so that the gang doesn't realize this and put themselves in harm's way trying to protect him.

From Redditor u/quackdamnyou:

Velma can be explained. See she worked as an intern at a lab that was working on developing a secret weapon: super intelligent canine warriors. She experienced an attack of conscience and escaped with one of the subjects, who requires daily doses of the active agent in order to retain his functions. Velma took to baking the drug into small cookies. Shaggy, not really understanding, tried one of these in a bout of munchies and now he too is dependent on the agent. A side effect of this alteration is that they have developed an incredibly high metabolism and insatiable appetite.

From Redditor u/IronedSandwich:

Quick note: depressants aren't drugs which give you a negative outlook on life necessarily, more drugs which calm you down.

So, in Scooby-Doo, Scooby and Shaggy love to eat Scooby Snacks. They make sacrifices for it (mostly facing their fears) and have huge amounts of energy building up to it. They also sometimes need more than one each. Also, the police haven't cracked down on it because A: Scooby-Doo is set in a financial depression and B: it's not normally for human consumption.

I'm saying they've become dependent on them to keep themselves from becoming fidgety and overly energetic (shaking!).

From Redditor u/themightyheptagon:

Scooby was bred as a super-intelligent test subject for the Soviets' space program, but escaped to America with a defecting scientist when he was a puppy. He has a speech impediment because he's smart enough to learn English, but his mouth can't form words perfectly. And the title Scooby-Doo, Where Are You! is a reference to the CIA searching for him.

Read the full theory here.

From Redditor u/Hurricane2410:

Their adventures take place in the Ghostbusters universe, after the events of the 2 movies. The reason that helping solve ‘ghost problems’ is a viable business is because the GBs established public knowledge of the threat. A bunch of small-time criminals are now taking advantage of this by faking ghosts to scam property.

Velma, Fred and Daphne are ghosts. Those 3 died back in the 1960's, which is whey they still have the dress/mannerisms of that period. Shaggy and Scooby are alive. They are just high all the time and don't know the difference between ghosts and hallucinations. They don't realize that their friends are ghosts. This is exactly why the 3 ghosts chose targeted them as business partners. They need a living person to interface for the business. They appeared to Shaggy during an acid trip.

A team comprised of ghosts and humans working together to hunt ghosts is not much different than Slimer working with the team of GBs. The goal of Fred, Velma and Daphne is to hunt down all these alleged ghost sightings in the hope that one of them is actually a ghost. They want to make new friends, recruit new ghosts. But of course, every episode turns out to be a dud so they gotta head to a new town to try again.

From Redditor u/RADDman:

First, let's look at ‘the gang’ (interesting word choice, guys!) and the individual members' roles:

Fred is a handsome and charismatic leader type, all qualities that make him a fit icon and head for a cult. Also noteworthy is that he seems to enjoy pursuing ghost stories.

Daphne never does much in terms of helping solve the mystery (I'm going off the original cartoon from the late 1960s). Whenever Fred comes up with a plan, chances are he pairs Velma with Scooby and Shaggy while he "goes investigating" with Daphne. She's clearly his clueless, hot groupie, mindlessly following the gang and only serving as Fred's girl.

Velma is a bookish type who does't fall into the societal standards of beauty, which could mean that she's not very popular with other teens. It seems obvious as to why someone as smart as her would want to follow Fred and Daphne around on wild ghost chases: it'd mean hanging with a pair of attractive teens, thus making her feel accepted. And isn't that what being in a cult is all about for plenty of people? She's also put to good use since her braininess means she could have a wide knowledge of legendary monsters and can solve mysteries (more on this later).

Shaggy can talk to a dog that certainly shares his personality. Everyone's heard the joke that he can understand Scooby's dog-speak because he's always blasted on drugs, but there may be something more sinister to it. As The Venture Bros pointed out, this is similar to the real-life serial killer known as "The Son of Sam", who claimed that canine demons ordered him to carry out his brutal murders. Maybe Shaggy is deranged along those lines, either because of a psychosis or being fed a whole lotta drugs by the gang in the psychedelic tour bus.

The gang consists of a bunch of teenagers dressed in more conservative, old-fashioned clothing, even though this is the late 1960s, when many youth were sporting colorful tie-dyes in rebellion against the old order. Mystery, Inc. might be trying to present themselves as better than the others (though why the hell they colored their van that way is anyone's guess). This is deceitful, as no one would suspect a bunch of homely-dressed kids to be a cult obsessed with the supernatural. This could also be the explanation for the seemingly-gratuitous inclusion of the term "Incorporated" at the end of the service's name.

So if they're hellbent on finding monsters as I believe, why do they always work so hard to unmask crooks in costumes? It's because they wanna make sure it's the genuine article. When they hear of a phantom scaring up a pier, they won't immediately believe it and try to gain power over it. Experience has taught them, time and again, that they have to take steps (solve mysteries) to ensure that this is a real paranormal creature they're dealing with and not just some phony.

Ultimately, their goal is to find a true monster or supernatural being and gain power over it. The world could only tremble at what comes next in their plot. The show Scooby-Doo, Where Are You!, which this theory is based on, lasted only 25 episodes from 1969 to 1971. Though the timing's slightly off, maybe in-universe, Mystery, Inc. became the equivalent of the Manson Family.