Are you a dedicated cosplayer/costumer? Do you class yourself as good, or heaven forbid, one of the best? Good for you.
I have a challenge for you. At the next event you do in costume, find somebody you barely know, somebody wearing a less well made costume of a character you like OR somebody who is very clearly new. Go up to them and give them a compliment.
If you really cannot bring yourself to compliment a costume below your own standards, then at least tell them that you are happy to see them costume as that character.
Go ahead. Brighten a newbie’s day.