-Fanservice of ANY kind, though yaoi seems to be particularly prominent and annoying because EVERYONE does it. I go to the masquerade to see awesome costumes and well-thought out routines..Not some poorly-recorded fanfic full of inside jokes that most people won't get and ending with Sasuke and Naruto making out.
-Bad dance skits. I mean, if you want to do a dance skit, fine! Those can be fun and entertaining, but please, please do lots of practice, especially if you're with a group. As an audience member, my heart breaks for you when you get up there and half of you look like you don't know what you're doing.
-Skits that run on for far too long. Short and sweet is the best, in my opinion.
people die when they are kawaii
next con: katsucon 2017