Anvilicious: "Pump Up the Panda" really hammers in its "be happy with your body" aesop, with two of the three plots being dedicated to it.
Ass Pull: Even by the show's standards, it's hard to believe that Roger knew that his daughter Blythe was able to talk to animals the whole time. There was little build-up or foreshadowing to this revelation whatsoever and almost completely comes out of nowhere.
The reveal that Whittany and Brittany's mother had been stuck in her room with a headache for about nine months, though they lampshade how implausible this is.
Blythe herself of all people is this. Some fans love her for her personality, design, and voice while others dislike her for being a Flat Character, mildly annoying, and so forth. Her human friends are also like this to some people.
Sugar Sprinkles, surprisingly, is now this after "Secret Cupet". Either you liked the episode and thought her love spells are funny, or you think she's a Karma Houdini whose actions in the episode were all sorts of wrong. Then there are those people who try not to blame the character for the writer messing up.
The Biskit Twins. Either you find their antics funny and endearingly incompetent or you think they're too mean-spirited or boring to appear in so many episodes.
Roger Baxter is either a funny goof or an annoying goof who sometimes gets in the way depending on how you look at it.
You either like Eliza Biskit's singing or find it annoying. Characters In-Universe tend to side with the latter.
"Blythe's Pet Project" has Blythe go into Sweet Delights looking for Anna Twombly's misplaced glasses. Once inside, Youngmee and her Aunt Christie launch into a bizarre vaudville musical number where all three get sucked into the lost and found box and find, among other things, the Holy Grail. Aside from an off-hand reference by Blythe in the next scene about musical theater, it's never mentioned again and has absolutely no impact on the plot.
"What Did You Say?" has Blythe trying to clear out her ears (she has a head cold) by sticking a towel in one of her ears, pulling it out the other and flossing back and forth. Not only is the gag quite a bit more... cartoony than the show normally uses, at least with human characters it is nearly always reserved for The Ditz in cartoons that do use it, to show how brainless they are, and Blythe is not that ditzy. It is never mentioned again and the rest of the episode treats her cold relatively realistically.
The "Humanarian" song number in "What Did You Say". It pretty much comes the hell out of nowhere, and is a series of eighties music video homages that don't have much to do with the topic.
In "Fish out of Water" when trying to find a way to cross the sewer, a bunch of sewer animals arrive, sing a song about building a boat out of junk, then immediately leave. Though this doesn't technically count, as the song is at least somewhat beneficial to the plot. But the fact the animals came the hell out of nowhere just to leave immediately after the song with barely an introduction. This feels like it should count.
The fact that the pets meet an actual alligator a few seconds later makes you wonder if this was done on purpose.
There are those people who thought "Secret Cupet" was funny or cute, or just try to ignore its issues, and those who think the episode was disgusting.
There have been mixed reactions over the writers bringing back previously likable characters Delilah and McKenna and turning them into Jerkasses.
The series finale is either seen as So Okay, It's Average or absolutely hated for not providing a proper sendoff to a fantastic show.
Die for Our Ship: Quite a few young Sepper (Sunil and Pepper) shippers have come to dislike Captain Cuddles and Delilah, even though the two characters were very nice to the main pets. Delilah did return and Took a Level in Jerkass, however.
Mrs. Twombly is this to some extent. It helps that Kathleen Barr, the voice of Trixie from Friendship is Magic, voices this character. Even better is her crazy cleaning fever season during "Eve of Destruction" that gained her more popular status.
The Biskit Twins' butler, who gets his groove on during a musical number in "Penny For Your Laughs", gets noticeable love from YouTube viewers.
The Biskit Twins themselves got a rather popular fanbase, mainly due to their ambiguous background story and humorous character.
Out of all the guest pets Madame Pom, Shahrukh, and especially Sugar Sprinkles are the most popular.
Episode 5 shows us that spending time with people who aren't the same as you will turn you into a mean spirited bitch, that it's ok to turn on your friend if they're also friends with someone you don't like and that people you don't like don't deserve second chances.
"The Hedgehog in the Plastic Bubble": If you become paranoid thinking you're going to die from a fatal disease you learned off of the internet which is 100% accurate all the time Don't bother telling your parent(s) right away, none of their business... instead let the paranoia fester until you become a complete delusional basketcase. THEN tell an adult. See Idiot Plot below.
What's in the Batter?: So you've lost an accessory...for suffering such a loss, it's perfectly acceptable to sabotage your friend's business, demand your friends rectify your own mistake, crash someones else's party, sabotage said party and physically assault the hosts unprovoked.
Two Peas in a Podcast: Lying to your friends so they spend more time with you and do everything you want. Then when they find out the truth, give excuses that what you did was justified and it's their fault for not appreciating you more.
A minor example here. Most fans are generally very blasé toward Josh. And since episodes like "Summertime Blues" and "Eight Arms to Hold You", some believe that Blythe actually has more chemistry with Russell.
And then there's Blythe and Youngmee. Holding hands frequently, cuddling their heads next to each other, etc.
Vinnie and Sunil, due to their Ho Yay-like friendship.
When Zoe Trent was revealed, comparisons to Twilight Sparkle were instantly made, while Twilight herself reminded many of Anarchy Stocking. Plus it's made funnier when certain fans imagine Princess Celestia using the royal canterlot voice and being as hammy as possible but as a diva.
In "The Hedgehog in the Plastic Bubble" Blythe has much less common sense than she normally does in order for the plot to work.
In "A Night At The Pawza", Fisher would have succeeded if he used his money and influence to bribe a "real" licensed building inspector to do the job, instead of a mook pretending to be one
The B-plot in "Petnapped!" is about Russel accidentally deleting the DVR recording of the "Duchess of Lancashire Lane" season finale. Blythe suggests reading the recap online instead. Why didn't anyone (especially Blythe) first check if the episode was available online? The pets might not have even needed to reenact the finale!
The Biskit Twins are this to some fans. "What's in the Batter?" just emphasizes their Woobie status after the pets crashed their relatively tame party. "Bakers and Fakers" also boosted their Woobie status at the later half of the episode being publicly humiliated during the judging of their cakes.
Vi from "Penny for Your Laughs" after Blythe inadvertently hurts her feelings.
The Scrappy: Penny Ling's ego can get annoying for some viewers. Especially in "Back Window" when it gets Russell and later all the other pets injured. It doesn't help that she is never called out for her behaviour is some episodes. In "Mean Isn't Your Color", she throws a tantrum and yells at her friends because of a mix-up with her outfit, something they weren't even responsible for. And in "Two Peas in A Podcast", she gets away with lying to her friends because she is able to guilt them by telling them she enjoyed being loved so much because they take her for granted.
Seasonal Rot: Overall, Season 4 has not been as truly well - recieved or considerably noteworthy to a lot of fans of the show as the previous 3 seasons before it... It could also be argued that Season 2 suffered from this issue as well, when the show actually had more of a fanbase to speak of than it did after that and of Season 3, in comparison.
Some were quite disappointed that "LPS: The Moosical", the episode that aired after the 100th official episode of the series was not an actual musical episode at all.
Some were very disappointed that Betty's journal was only the focus of about 4 episodes in season 4, which is part of Seasonal Rot the show suffers from here - that, and the lack of seeing what Betty (could have) actually looked like...
Youngmee is looking for a pet to call her own in the first half of the fourth season, but has been unable to find one. Some people assumed that she could have adopted fan-favorite Sugar Sprinkles since she's a stray cat with no home who lives in Youngmee's place of work and could've gained more character development. However, the two never once interact in the series and Youngmee ends up adopting a Satellite Character for a pet in the end.
All of Blythe's human friends besides Youngmee and Mrs. Twombly were completely absent from the series finale, while the Biskit family only made a brief silent cameo. Also, only a small handful of season 4 guest pets returned, rather than fan favorites like Buttercream and Sugar Sprinkles. To be fair to the writers, they didn't know it would be the series finale.
Zoe reveals that she's grown great disdain for cats in the series finale after her stint with Delilah, but Blythe and the others are attempting to gain a famous cat celebrity to help make a film to boost publicity for the pet shop. However, Zoe never once interacts with Felina Meow, a famous cat diva who appears to be her Evil Counterpart, at all during the finale and gets Demoted to Extra.
Some were disappointed that Mrs. Twombly and Mrs. Biskit never got to interact.
Too Good to Last: The show was cancelled after four seasons due to the toys not selling well.
Ugly Cute: The "wolf-i-fied" versions of the pets who aren't Sunil and Vinnie that star in the "Wolf-i-fied" number in "Door-Jammed".
Penny Ling after Pepper's "jokes" about her. Taken up a notch in an episode of Penny repressing her own feelings about a man suit she assumed was her outfit for the ball. And once again after Zoe and Pepper getting into a fight on whose party theme is suitable for her.
Blythe during the episode "Helicopter Dad", especially when she breaks down crying after telling her dad to leave her alone.
Zoe Trent on the latter half of "Terriers and Tiaras".
Sunil in general can be seen as this. His magic tricks often blow up in his face and he's pretty much a Nervous Wreck. Taken up a notch in "Lights, Camera, Mongoose!" and as of season 2, he's been washed down a river, nearly drowned and recieved unwanted fame in the Meme episode. On top of this, Blythe referred to him as "Worrying Mongoose" once he became a famous meme instead of his own name which probably depressed him. Then there's future episodes like "Super Sunil" and "Sunil's Sick Day" which will most likely make him an even bigger woobie than he already is.
Ollie in "Eight Arms to Hold You", with his story of how he arrived in Littlest Pet Shop serving only to exemplify how pitiful his existence is.
Sweet Cheeks from the episode "Pawlm Reading". He oozes Moe to such a degree that he even rivals Penny and Sunil and on top of that, he's a poorly socialized Shrinking Violet, cooped up in his owner's purse who is scared of even touching grass. Also, his Phony Psychic owner assumes he loves nummy nuggets which he hates.
Poor Russell, you can't help but feel sorry for him in "In the Loop" when he was trapped in a time loop causing the day to repeat over and over again almost completely losing his sanity. As well as his "quilling" condition in "The Hedgehog in the plastic bubble" he was more or less heartbroken because he thought he'd never be safe enough to around his friends again.