The Garbage Pail Kids prove themselves to make Juice and his gang of bullies look like saints in comparison— they steal things, vandalize property, harass others (to the point of starting fights) and even insult the two people who look after them.
Captain Manzini is intended to be the Big Good, but the most heroic thing he does is spring the Garbage Pail Kids from prison... so that he can imprison them again inside a trash can.
Fridge Horror: If they come from space, does it mean there's a whole planet of those atrocities?!? If so, it's all the reason we need to build a functional Death Star.
Jerkass Woobie: Tangerine uses Dodger and the GPK to make herself look good as a fashion designer and even ends up betraying them. At the same time though, one could feel sorry for her: it's implied that Juice is abusive as he does rough her up at times.
The Garbage Pail Kids themselves. They probably didn't intend on making them so horrific-looking, but they are.
The whole concept of the State Home For The Ugly.
Padding: There are several long, dragging scenes of the Kids interacting. Typically scenes like this would be used for character development or exposition, but in this movie a lot of the dialogue scenes contribute very little to the film's story. Particularly of note is a three-minute sequence of the Kids playing a prank on a random man by redirecting a sewer pipe into his hot tub.
Rooting for the Empire: As... idiotic as the idea of the State Home for the Ugly is, the fact that they want to apparently outright murder the obnoxious protagonists actually makes some people want to root for them merely for that reason alone. The "kids" belong in that place, no question about it.
Snark Bait: The only reason most people who are well-informed about this movie might want to watch it.
Special Effects Failure: The ship at the beginning of the film is a model that clearly looks like a "not-quite finished" model in front of a half-assed painting of Earth.
The Garbage Pail Kids themselves; Already too creepy and ugly for words, it's painfully obvious that they're all just crudely made rubber suits, with poorly functioning mouths and lifeless eyes to boot.
Tangerine and Dodger hitting on each other. She is in her twenties (or, at least, looks so) and he is fifteen. Shockingly, Tangerine's actor is only a year older than Dodger's, which somewhat sweetens the blow.
The Kids themselves who fart, piss and threaten people every other minute despite wanting to be acknowledged and one even has a knife. They are just nasty in every sense of the word.
Uncanny Valley: The Garbage Pail Kids are little people in horrible, horrible rubber outfits. The suits are so badly designed that their mouths can't even close. Your dreams will be haunted.
Unfortunate Implications: Everything about the State Home for the Ugly. The fact that anyone bound for this place is implied to be executed for such superficial reasons only drives the insult home even further. Although, some people feel that the kids are so horrible that executing the nightmarish abominations would be firmly justified.
What Do You Mean, It's for Kids?: This film got away with a PG rating and is based on a franchise popular with boys aged 9 and up. However, amongst many, MANY other things we have underage drinking, thuggery, assault, a few curse words, near-nudity, implied genocide, sexual abuse, and murder. This actually drew the wrath of parents plus cast member Jim Cummings and got GPK withdrawn from theatres only weeks after its premiere, which resulted in the film becoming one of the bigger box office bombs of 1987 and derailing the franchise as a whole.