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.
Ass Pull: Hana having a secret twin sister in the Ojamajo Doremi 16 novels in order to explain the witch election system. Oh, come on, how could an equally powerful baby be kept under wraps and never hinted upon all this time? Not to mention, they're using this to justify how queens get elected and still Handwaveing away that all witches could have had a chance at being the queen in season 1, not babies born from the blue rose.
And then there is the fact that twins are born from the same rose, such as the case with Majo Vanilla and Majo Monroe.
Add in the fact that Hana was the only baby in her rose and we've got a pretty massive Plot Hole.
Base Breaker: Was the dub a heavy Bowdlerization that detracts the original moral values of the show, or was it a tolerable adaptation with good musical numbers?
Hana. Is she a Creator's PetMary Sue who was The Load during her debut season or a character worthy of being just as loved in real life as she is in-universe?
The above Ass Pull. Some fans legitimately don't mind it.
Canon Sue: Some fans consider Onpu to be this, although mentioning it starts flame wars. Her detractors claim that she qualifies due to being a famous and beloved actress, model, and singer, a better witch than the others, someone who is often looked to for (rarely-questioned) advice that any other character could have given and is portrayed as being loving and sweet even when she can be rather rude. However, she is occasionally proven wrong or portrayed as being a jerk (particularly when she first shows up), and most Magical Girl characters are like this anyway.
Hana gets some hate because she is essentially this as well due to her status of being the Sixth Ranger with a Special Snowflake Syndrome. She's so powerful she doesn't need to be in Magical Stage, she's usually the one who accompanies Baba through the door of the former witch queen's heart, she's the only one capable of destroying the curse of the brambles (with the help of Pao), she's crowned the future queen of the Witch World, and she's well-liked by everyone. Doremi and the girlssometimes spoil her because she's cute, and all the boys in class 6-1 (except for Kotake) have had a crush on her at some point. In fact, all the members of the FLAT4 were hitting on her during their first reunion episode.
Creator's Pet: Hana has shades of this, especially when one takes into account that other characters tend to give her praise even if she really had nothing to do with it or was a complete accident. Already most of the fanbase found her annoying due to her role as The Load in the first two seasons she appeared in. Unlike Pop, the other Scrappy, Hana only received more unwarranted spotlight due to her Eleventh Hour Super Power come Dokkan.
Crowning Music of Awesome: Being a series that initially uses music as a theme, this was bound to happen. At the time of writing, only a handful of the music tracks have been uploaded for easy listening.
The Magical Stage theme for Dokkan is easily the most epic out of them all.
The recurring theme in "Secret of the Frog Stone."
Die for Our Ship: Shiori and Fujio are sometimes this for Hazuki × Yada fans and there is some decent-sized Ship-to-Ship Combat between Kotake × Doremi, Akatsuki × Doremi fans, and Doremi-yuri-pairing fans. Imagine how the fans reacted when Aiko was given a Love Interest in Naisho where she neither admitted nor denied attraction to him, causing an uproar from fans who paired Aiko up with Nobuko/Momoko/Onpu/Leon.
Ear Worm: Just about any song done in the original or 4kids dub.
The same could be said for the Image Songs, openings, and endings.
Also, Marina and Sachiko by spades. Although they were just side characters and haven't been featured in an episode together, they seemed to be popular characters because they were featured on more merchandise than even Majo Rika and Lala.
The FLAT4 could count too, since they were only present in Sharp and didn't appear again until Dokkan.
Family-Unfriendly Aesop: Episode 19 of S1 had Hazuki get kidnapped. Instead of giving the moral of not talking to strangers, the kids are told that if they help the kidnappers get their dream jobs the right way, they'll begin to repent and come to their senses.
Dokkan episode 24 has this too. Dressing up as a super hero and going around causing mischief in a misguided attempt at "heroics" is asking for trouble. This is especially evident when Hana disrupts a shooting for "Battle Rangers" and causes a severe deviance from the script. Realistically, this is a good way to get in trouble with various studios and, potentially, the law.
Fan Dumb: A lot of episodes, moreso in Dokkan, which has more themes of transitioning into pre-adolescents than the rest of the series, have so much depth and concept to them that many fans actually overlook the intentional messages in them. For example, in episode 9 of Dokkan, Hazuki gets jealous when Masaru Yada starts becoming better friends with local Ill Girl Shiori Nakayama. Up until then, Yada's only female friend was Hazuki, and naturally, Hazuki feels uncomfortable realizing that Yada is opening up to people other than her. The episode mainly deals with Hazuki overcoming changes in friendship, but to Hazuki × Yada shippers who don't care? "OMG, why is that black-haired girl getting in the way of my ship, roar!"
Fandom Berserk Button: Using any terminology from the 4Kids dub is practically having a death wish in the fan community.
Fan Fic Fuel: Nozomi and Fami had a lot of potential as characters and several loose ends. Naturally, they do get a level of attention from Fan Fiction writers.
The same could be said for any minor or one-shot character.
Fanon: Fami's surname being Harukaze. Some people forget that since she's Doremi's granddaughter, Doremi married someone and by japanese tradition adopted the surname of her husband. Plus, if we assume Doremi had a daughter, the daughter also adopted the surname of her husband. To sum it up: unless Doremi divorced (or not even married to begin with) and re-accepted her maiden's name and then had a son, or a daughter who also divorced/not even married, Fami's surname is not Harukaze. Then again in these days, women can keep their surnames. But the most probable reason is to not reveal who Doremi is going to marry. If so, then expect a Retcon.
The FLAT4 having surnames. The most popular so far are Akatsuki Shidoosha, Fujio Kashikoi, Leon Sokuryoku, and Tooru Kounna. Sure, they start going to school in Japan in Dokkan, but apparently the writers didn't think it was important enough to mention what those surnames are.
Girl-Show Ghetto: 4Kids Entertainment only wanted to license this series alongside Winx Club for the Foxbox because they wanted to expand their channel demographics, since they had shows that mostly appealed to young boys.
Growing the Beard: The later seasons are generally considered to be far better in overall quality.
It Was His Sled: Not a twist ending, but almost any reference made to Hana by the fandom is to her "grown up" form. It's not new or surprising or interesting when one sees it happen in Dokkan because of this.
Lots of people in the fandom refer to the former witch queen by her real name, Majo Tourbillon, which dispels any of the mysterious and menacing images Sharp and Motto' set her up with.
Les Yay: A lot among the girls. Some of the most notable are Doremi/Onpu, Nobuko/Aiko or Miho, and (if episode 3 of Motto and the second movie are anything to go by) Aiko/Momoko.
Rescued from the Scrappy Heap: Onpu was very much disliked during the first season. She used magic to solve all of her problems and even used forbidden magic for trivial purposes such as getting her mother to take her out for dinner in order to avoid having to eat green peppers. Although she isn't entirely to blame for her misuse of magic when you consider who her teacher is. However, even without magic, she was still kind of a prick and speculated that the reason Tamaki never gets punished by her father is that he doesn't love her and says it out loud in Tamaki's face. She does get better near the end of the first season though as the last two times she used forbidden magic was to help another girl with her audition and to save the other girls from being turned into witch frogs. In season 2, she whole heartedly joined the other Ojamajos, and her popularity made a significant jump to the point where she was the only other Ojamajo Doremi character who made it very far in the fan-driven 2002 Anime Saimoe Tournament
Ron the Death Eater: Some fans prefer to portray Majo Ruka as an outright villain in certain stories due to her being an antagonist during the early part of S1. The same could be said of Oyajide due to his role in the second half of Sharp, despite repenting for his mistake.
There are still some fans who portray Reika Tamaki (designated The Bully in Doremi's human life) as a complete Jerkass especially because of what she did to Momoko early on in Motto! This is common among fans who have never liked her since her first appearance or haven't seen her Character Development episodes. It's definitely true Momoko hated Reika at first for constantly trying to one-up her, but she and Reika become best friends over the course of the series.
The Scrappy: Since Pop wasn't given much of a role in the first place and was mostly a Bratty Half-PintAnnoying Younger Sibling for almost two seasons, she tends to be disliked by the fanbase. Most of her detractors claim that her presence in the story was unnecessary, and her personality pre-Character Development didn't help either. Hana is also considered one of the least favorites of the fan community due to her qualities of being the Canon Sue (read: unrealistically perfect), a Dojikko (read: causes trouble), and somewhat of a Bratty Half-Pint when she gets upset (read: causes more trouble).
Out of all the classmates, Tamaki is probably liked the least. She brags about how her father never punishes her as opposed to the other girls in her class and thinks that punishing your child is "barbaric". She makes fun of Momoko and Hana during their respective first days of school, Momoko for technically being a foreigner and Hana for acting like a toddler.
Other than Tamaki, some of the male classmates were scrappies for one at least one episode. Notably the SOS Trio for teasing Naomi, and for the idiotic strategy they used to "beat" Mutsumi in a wrestling match.
Strawman Has a Point: Ojijide's actions during Sharp were wrong in the end, but they were made in the best interests for the remaining Wizards.
Uncanny Valley: During episode 22 of Sharp, Oyajide disguises himself as a woman to try and sneak into the school recital in order to spy on Hana. Yuki wasn't the only one who was disturbed by his appearance...
Unfortunate Implications: In episode 24 of Dokkan, the ganguro high school girls Doremi bumps into are pretty rude to her until Hana makes them nicer with her magic. Note that the high school girls originally had darker skin before Hana intervened. When Eastern values of beauty come into play, it's not very hard to see the racist undertones.
Viewer Gender Confusion: Kayoko, whose extremely short hair and ambiguous voice likely threw off people until Doremi states that she was a girl (likely tipped off by the red schoolbag).
The Woobie: All the main characters and nearly all the classmates at some point.