I'm only responding to this with characters you're not supposed to hate because in terms of characters like Morrible(played by the amazing Carole Shelley) it's more I love to hate. Okay:
Adult Cosette-lots has been said about her.
Rauol-I was gonna be the first to say him, Phantom Tenor, oh well. In addition to getting in the way, he's just a total bore compared to the Phantom.
Maria(WSS)-okay I don't completely hate her, but she is way too perfect and is basically the cause of most of the deaths in the show and really doesn't think.
Maybe I'll think of more later.
One more note: Shipoopi isn't the greatest sung song, and the Music Man is certainly not one of my favorite songs, but there's two things I must defend: 1) Shipoopi dance #1 is extremely difficult to play and 2) Shipoopi dance #3 was an awesome song to play and most of the pit's favorite and we sounded really good on it, so I think it's a good number because of pit. Okay, end rant.
"If there was a Mount Rushmore for Broadway scores, "West Side Story" would be front and center. It snaps, it crackles it pops! It surges with a roar, its energy and sheer life undiminished by the years" - NYPost reviewer Elisabeth Vincentelli