If I were an extremely talented composer, I'd write a musical so dazzling, so emotionally moving, so technically beautiful that the industry would have no choice but to produce it. BUT I'd put in one song that's really bad as a joke.
And I'd make it a song that's so essential to the plot and character development that you can't cut it. And it would be led by the show's least interesting and relevant supporting character (think, like, the love interest's mom or something), but it would be all about and sung to a MAIN character, who has to be onstage the entire time without singing anything. But it wouldn't be one of those songs you walk out of the theatre remembering, like an opening number, an act one finale, act 2 starter, 11'o clock number, or grand finale. It'd just be innocuously wedged midway through one of the acts and take WAY too long. After the show, audience members would kinda remember one part of the show dragged, but not really recall the details. But creative team members would AGONIZE over it!
It'd be a totally different musical style from the rest of the score and require strange instruments. It would be difficult to sing, but not in a way that actually sounds technically impressive to an untrained ear, and written for a character who is otherwise an 'actor who sings' type. It would be extremely wordy and full of tongue twisters, making it easy to mess up. It would be written as a dance number with a long dance break, but keep changing tempos in a way that's hard to choreograph to. There would be a big costume and set change written into the dance break to keep them from cutting the dance break. The dance break music would sound nothing like the melody of the song.
The repeated chorus would change a little in tune and lyrics each time. Each verse would have a different number of lines. I'd write orchestrations for brass instruments that keep clashing with the vocal harmonies, but only SLIGHTLY, and there would be an incongruous 'oompah' tuba throughout regardless of the tempo changes. The repeated chorus would be built around a figure of speech that sounds like it COULD be euphemism for something gross, but not necessarily. Oh, and the song would center around a character with a name that doesn't rhyme with anything (say, "Henry,") so the song would keep rhyming with itself or reaching for slant rhymes and forced nicknames not used elsewhere in the show.
And I'd REALLY twist the knife in by using motifs from that number in the show's finale, but make them WORK somehow. Transform it into something beautiful, giving false hope that the song itself could be beautiful, too. (It cannot.)
And through it all, I'd aim for a single goal: making members of every creative team to produce the show stand there with their hands on their hips and saying, "The number doesn't work." They'd gather together and try to figure out how to fix it. But I made it unfixable. I took every single loose end and tangled it into a Gordian knot, and there's no way to take it apart without taking apart the whole show! My cursed gift to the art world! My poisonous confection! My decadently stained masterpiece!
Unfortunately, I cannot compose at all, so this would never happen.