I'm having my 3rd Annual "Ugly Christmas Sweater" Party this weekend, and even thought I wasn't Mustachian back then, the idea was to have a Holiday get together and also make a fun "theme". As far as being anti-mustachian, in my experience with it has been exactly the opposite, with pretty much everyone raiding Goodwill or their Mother's (or Grandmother's) closets for an extra ugly version.
Also, since this event has become popular, everybody saves their sweater, so again, my own experiences haven't really been all that anti-mustachian.