For me, it was Cerulean Sins. I already knew that the series was devolving into port, and after not reading for so long after Obsidian Butterfly, I finally struggled through Narcissus in Chains, and got maybe ten pages into CS before I got fed up. I was so excited that Anita was actually doing a zombie raising, and then Asher showed up to whisk her away to the Circus and I just put the damn thing down and took it back to the library.