
Many protect themselves from scrutiny by claiming they "cosplay to express, not to impress". They think the can distinguish themselves from trash by pretending they're not show-offs. I call bullshit on their futile act for a variety of reasons, some of which I will detail below.
Good day, bad day. A successful costume is that which effectively catches the attention of passersby and con-goers who stop to take pictures of. If everyone with a camera points lenses at you, your outfit is top tier. You deserve a pat on the back. When nobody gives a damn about your existence and you spend the next couple of hours wearing outrageous clothing unnoticed, it is considered a failure. Which part of this says "I'm not trying to impress"? Peer recognition is the name of the game. Expression of oneself comes at the expense of hoarding attention.

On-stage mayhem. Nothing screams attention whore louder than climbing the stage in front of an audience just so you can gratify your need for acceptance. Unfortunately, the cosplay catwalk is nothing more than a freak show and your demographic is a bunch of socially inept personalities so they don't really mean much.
Online pic spam. What exactly do cosplayers hope to express by infecting the Internet with dozens upon dozens of their pictures? Painters express themselves by infusing their thoughts and emotions into every element and color in their pieces. Writers create characters and events that tell a story. Musicians use music as painters do with paint.
Cosplayers? Cosplayers do nothing but try to look pretty (or horrid) by imitating the works of others and often failing at it. The pictures they post are of the camwhore variety - plenty in numbers but each one looks like the next, only with a slightly different pose or exposure. If they're trying to say "Hey, look at me, I'm retarded!" then message fucking delivered.