I don't really gravitate towards popular series very often - not because I avoid them like the plague, but I like older series and well, usually that's not what is very popular at the time - only whatever is new. In recent years the only fandoms I've been a part of that were really popular were Ouran and Gurren Lagann, and I never personally had any problems associating with or cosplaying with my fellow fans. I've heard stories, and that's pretty much it. Personally I haven't had any negative experiences. Sure, you are bound to get younger fans in some series, and you kinda have to forgive them for how they act sometimes - but when it comes to damaging property, annoying people, etc. then the line gets drawn.
2014 Conventions :
Katsucon (Washington, DC) - Megacon (FL) - Colossalcon (OH) - Anime Weekend Atlanta (GA)
Upcoming costumes : NiGHTS from NiGHTS: Journey of Dreams, Princess Kraehe (anime) from Princess Tutu, and Zidane Tribal from FFIX!