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.
Audience-Alienating Premise: Exactly why did Disney think families would be interested in a musical period piece that's played mostly for drama?
Base Breaker: The stage adaptation. Plenty of fans of the original movie can and will admit that they consider the stage adaptation to be good, and even better than the source material. Some fans like both equally. But there's a group of fans of the original movie who will get pretty vicious over the stage musical and the amount of love it gets, plenty of them complaining about how nobody likes the movie anymore.
Sarah and Katherine. Better off to just not talk about them. Sarah is still considered The Scrappy by most of the fandom.
Ear Worm: Itís a Disney musical, after all. King Of New York is particularly catchy.
As of the stage musical... Something To Believe In, Watch What Happens, Santa Fe, Seize The Day... As much as the original movie had ear worms, the stage adaptation has even more.
Ensemble Darkhorse: Oy. Okay, rule out every main character. Then every female character. Then everyone over the age of, say twenty-one and under the age of fourteen. That character will have enough fangirls to qualify as this.
Spot Conlon, especially.
This troper can clearly remember thinking Mush needed to spend FAR more time with his shirt off.
The age thing is arguable, given that almost half the dancers that have fangirls were over twenty-one. And more than a couple of them were under fourteen. (Dominic Lucero, Brian Friedman, and D.J. Dell'Osa are all particularly well known examples.)
Kid Blink is quite popular among the fanbase. Just look at that smile.
It could have something to do with the blatant sexual tension between the two leads...
Case in point: after the barely-there girl and David get saved from attackers, watch carefully. Jack gives the girl a perfunctory "You're okay, bro" slap on the back, while he almost caresses David while finding out if he's okay. The Ho Yay is strong with this one...
A case can also be made for David and Denton: Denton first goes to David, saying, "You look like the man in charge," when Jack Kelly is the one who just led the big song and dance number. David is the one Denton hands his card to. David seems irrationally angry when Denton is reassigned. And later, how do they know where Denton lives...?
Let's be real, this is a movie with almost an entire cast made up of young, nubile boys who live, sleep, and shower together (not to mention sing and dance). It's like a perfect storm of homoeroticism. If you took a shot every time something gay happened, you'd be drunk before the end of the opening song.
MST3K Mantra: Among (many) other considerations, why do these kids have jobs as unskilled laborers? Look how well they can dance!
Narm Charm: The movie tried to work Disney magic on atypical subject matter. For some, this results in the subject and tone of the film clashing in a very stupid way. For others, the fact that it's so over-the-top just makes it all the more awesome. Also, it has Theodore Roosevelt.
For one thing, while we have some Crowning Music of Awesome in the musical, with Seize the Day and The World Will Know, the Final Love DuetSomething to Believe In has got to be the worst-written and most generic song of the soundtrack, with such lyrical gems as "We [were] never meant to meet/And then we meet, who knows why?" and "I thought I knew what love was/Now I'm learning what is true:/That love will do what it does.".
Ships That Pass In The Night: Hoo, boy. Aside from all the shipping for the background characters (who have perhaps ten lines between them all, and there's thirteen of them), there's Spot and Racetrack, who are one of the fandom's three OTPs, and Blink and Mush.