These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: The Amazing World of Gumball
Abandon Shipping: The scene in "Halloween" where Darwin kisses Carrie left many Gumball/Carrie shippers a little bit dead inside.
Awesome Music: Mr. Robinson's performance at the end of "The Debt".
"She's a lady, a fine lady!"
"You gotta think big, think smart!"
"Warrior, Be The Warrior!"
"We enjoy it while we can, we enjoy it while we're kids! We enjoy it while there's still time to make the most of it!"
Base Breaker: Nicole is one of the least popular characters among the target audience, but older fans tend to love her.
Though the show can be quite bizarre regularly, The Sweaters takes the cake. Even Gumball and Darwin think things have gone bizzare.
"The World," an entire episode devoted to showing that everything in Elmore (and possibly the universe) really does come to life in the form of multiple short sketches. It's about as weird as it sounds.
Dude, Not Funny!: The sudden Dead Baby ComedyBlack Comedy Burst in "The Job" seems incredibly out of place for such a lighthearted show, even in the name of Black Comedy, and it's more disturbing than actually funny, especially since they hold on the image of the pizza parents disturbed faces for several seconds.
Growing the Beard: Season 2 saw a massive improvement for the show with it's Art Shift (though that's a bit of a Base Breaker right there for some who liked the original character designs), the stories also became more structured and coherent.
Hilarious in Hindsight: During "The Sock," Darwin says to Gumball that he walks like a princess. Cut to "The Dress" where he actually looks like a princess.
Bobert. All he wanted is to have emotion. After finding said emotions and he took Gumball's life. Rather than try to teach him right from wrong, Gumball simply decides to "Reboot" him, deleting his memories and emotions.
William can't physically speak, but he hasn't realized this until after he attacked Gumball and Darwin for ignoring him.
Nausea Fuel: In "The Knights", Gumball tries to get Penny's father to like him by cleaning the sweat from under his arms while he is jogging, and after he tells him to quit, Gumball then washes his mouth with the same rag. Ew.
Parody Sue: Alan turned into one of these about halfway through Season 2, being shown to be ridiculously nice and perfect. A recurring gag is how this winds up biting him in the ass.
Purity Sue: Darwin is constantly portrayed as unfathomably pure and innocent., to the point where the very embodiment of Jealously itself inhabits and body and says "I'm actually very content with my life right now"
Though there have been several times where he's shown to be as petty and jerky as Gumball and does some rather questionable acts, like kidnapping Tobias' mother to get a video game back. The only reason he gets more leniency is because he's still adjusting to the whole sentience thing.
In fact a recurring plot/gag is that whenever Gumball develops a serious problem, Darwin will snap him out of it... only to develop the exact same problem, only even worse. (i. e. "The Phone", "The Sidekick", and "The Banana")
The Scrappy: Richard. The episodes that focus on him tend to display him as a Jerk with a Heart of Jerk and have weaker plots. The stupid contests were more tedious than humourous.
"The Job" is an exception, many fans feel that it is the best episode so far because it feels like watching an episode of Regular Show. That alone makes some people believe that Richard is Rescued from the Scrappy Heap. Either that fact or the fact that if Richard holds down a job, the universe starts to destabilize definitely helps.
Richard's song in "The Hero" has some similarity with the Malvina Reynolds song "Turn Around"; aside from the fact of the subject being both about seeing their child grow up, there's also how they sang the words "my little one".
A blatant soundalike of Herbie Hancock's "Rockit" plays over the senior citizen dance sequence in "The Extras", right down to the record scratch breaks.
They Changed It, Now It Sucks: The streamlined character designs in Season 2 has drastically changed the basic movements and mannerisms of the Watterson family. In some ways they now move more fluidly, but many other times, exceptionally choppy. The characters themselves aren't as colorful as they used to be, as if they're constantly in a slight shadow.
Banana Joe and Clayton both having eyebrows. For some reason, a bit of the overused Dreamworks Face comes into play which doesn't really settle well for these two as it made them look...less-charming.
The news that Gumball and Darwin will have new VA's in season 3 hasn't gone over well with the fandom.
They Wasted a Perfectly Good Plot: A lot of fans were disappointed by the episode "The Genius" because of the boring climax of the episode, even though the episode could've easily been more epic with something like the family going to the research facility to rescue Darwin.
Ugly Cute: Kenneth. Anais even mentions this trope by name when describing him.
"Well, I guess you're kinda ugly-cute."
Richard, Baby!Gumball and some characters can be this.
What Do You Mean, It Wasn't Made on Drugs?: The entire show, but special mention goes to the opening. It should be noted, however, that the reason why the show looks the way it does was because it originally was supposed to be about outcast cartoon characters attending a rehabilitation school that makes them functioning members of society. Since Cartoon Network found that premise to be too depressing (and possible protest bait for those with real-life developmental and social anxiety issues), the show creator changed it to be about a cat and a fish having weird adventures in their weird town and the rehabilitation school was changed to a normal junior high/middle school.