Western Cosplayers, or Westerns, are what pure Asian Otakus call white people, who over-cosplay, try to convince themselves that they are Asian by reading manga and drawing anime, (when really, half of the time it is not even close to anime), using Asian words and/or references in everything they say, and just plain trying to copy Asian Culture.
They are simply just jealous of the fascinating Asian Otaku Culture that originates all through ASIA.
"Wow! Is that the new Vampire Knight bag? Kawaii desu!"
"Sugoii! Your outfit is amazing!"
"Western Cosplayers? We ALL can cosplay good!" (When that's not ENTIRELY true, at all.)