1950 March,F. Towner Laney,“Fanzine Scope”, inSpacewarp, number 36, page 10–17:
Under the title "Stfans -- Race of the Future", Joquel dissects the "fans are slans" theme which back in 1941 was being considered with a surprising amount of seriousness, and comes up with the obvious conclusion of phooey.
1959,Eney, Richard "Dick" Harris,Fancyclopedia II:
FANS ARE SLANS Literally understood, "fans are superman mutants" -- or, at least, "fans are smarter than most people" -- but actual semantic content is according to the mood and attitude of the user.
2000 April 27,Pete McCutchen,“Re: Mr. Ordover, I disagree”, inrec.arts.sf.written, Usenet, message-ID <4uvggsgbbt3gsqrobf2o1prj0offlhpuch@4ax.com>:
"Fans are slans" is a way of saying that we're smarter than other people. (Which is true, actually, but rather impolite to bring up in mixed company.)