Unfortunately no setting can get darker than the Fascist, segregated world Jim Henson so beautifully crafted in his Creature Workshop cinematic universe. There are three types of people in Jim Henson's world: Muppets (Kermit, Fozzy, Swedish Chef, etc), Humans (Jack Black, Michael Jackson, Dwayne the Rock Johnson, etc), and Monsters (Elmo, Grover, Cookie Monster, etc.) The humans are obviously top-dog in this society, taking roles above the muppets and the monsters and often taking their pick of muppets to fill similar roles for amusement. Our main muppets, for instance, all have better careers than other muppets. They produce their own shows while the Swedish Chef is filmed bumbling and getting hurt for everyone's amusement (while the OTHER slapstick is clearly scripted...) But his pain and suffering pales in comparison to the monsters.

Forced to live in poverty on Sesame Street, with their stores run by humans, the monsters are fed chemicals in their food to keep them impressionable and ignorant while their human "caretakers" (really just agents keeping a close eye on the monsters so they don't revolt. They're ready to kill them at any second) "teach" them lessons, knowing full well the monsters will never be able to fully comprehend those lessons. 

Monsters are filmed living "nice, peaceful lives" and shown to an ignorant populace so no one tries to free them of their segregation. While we may laugh at the antics of Oscar the Grouch, remember that he onlh lives on Sesame Street because he was stolen away from Grouchland, never to return.

Of course, some monsters get to live in relative luxury. The three most prominent being the Count, Bert, and Ernie, who live away from the others. For cryin' out loud, Bert and Ernie can afford clothes while Elmo goes around naked most of the time. Why do these three get more than the others? Because they snitch on anyone trying to leave, obviously.

Its really messed up.