Subverted: Propaganda portrays the colonies as shining beacons of civilization and the Earth as a Wretched HiveCity Planet. When someone born off-world does return, she's surprised by how average (even superior in some ways) she finds Earth life to be.
Double Subverted: ...But the spaceports are bustling, futuristic oases compared to the rest of the planet.
Parodied: People go on and on about how primitive, polluted, war-torn and generally terrible Earth is... when we finally see it it's exactly like Earth is today.
Zig Zagged: With interplanetary travel so expensive and time-consuming, the vast majority of colonists have never seen Earth, so their stories are based on hearsay, myths and propaganda. Ask 10 people and you'll get 15 contradictory descriptions of what life on Earth is like, with some people looking through the Nostalgia Filter at the Cradle of Humanity, and others dismissing the barren husk we used up and had to escape from.
Lampshaded: "Grandpa, why don't you ever talk about the Old World?" "When I was your age, my grandpa used to tell me how beautiful Earth used to be. My daddy used to scowl and yell at him, tell 'im he was livin' in a dream world. Then one day, we packed our things and got on the elevator, and I looked down at the black and red, the yellow clouds drifting across the land, and I guessed my daddy was right."
Invoked: The One World Government starts making propaganda about how much better off-world life is to encourage people to buy into long-term Terraforming contracts and stick them out.
Exploited: People having given up on Earth as a place to live, and with everyone of any power and influence living off-world, there's no pesky conservationists to hinder its descent into an even worse state, a blasted industrial hell run by MegaCorps and staffed by powerless serfs working for the promise of a ticket out.
Defied: Appalled by what we did to it, humanity declares Earth an Area of Outstanding Natural Beauty and vetoes all further industry and construction, re-terraforms it and allows it to gradually develop into an Arcadia for rich tourists and educational trips.
Discussed: A Human Popsicle wakes up on a Generation Ship, and immediately asks what the new capital of civilization is now that our best and brightest have doubtless left Earth behind.
Deconstructed: The colonists are all people who wanted to leave Earth in the first place, and cognitive dissonance has only exaggerated their feelings by convincing them they must have had a really good reason for leaving. Meanwhile, Earth natives have plenty of their own stereotypes about how nasty, brutish and short life is in the colonies. The reality is that there's a lot of variation in living standards wherever you go — settled, terraformed planetary colonies are nicer than frontiers, large scientific-research Space Stations are nicer than those dedicated to asteroid-mining, etc — and Earth, as today, is no exception.
Reconstructed: While the above is true, the pollution, overpopulation and nuclear fallout on Earth put it several steps below the nicer parts of the Solar system.
Played For Laughs: A new arrival from Earth is treated as a Funny Foreigner (or should that be Amusing Alien?) from a stuffy, backwards planet.
Played For Drama: There's considerable diplomatic tension between Earth (which still has most of the military technology in existence and is constantly on the brink of World War X) and the colonies, who look down their noses at the homeworld and are sorely tempted to declare independence.