One of Truman Capote's short stories, The Thanksgiving Visitor, starts with "Talk about mean! Odd Henderson was the meanest human creature in my experience. "
I take it that the "mean" in the exclamatory sentence is a collective adjective referring to a group of mean people, but shouldn't collective adjectives be always preceded by "the"? If yes, what could be the reason for the author's omitting it? If no, what may be the cases when "the" could be omitted before a collective adjective?