According to a poster on Newsarama, all the letters (likely fake, of course) in crappy music magizine "SPIN" were from mutants. More specfically, mutants of the X-variety: http://www.newsarama.com/forums/showthread.php?t=71421

Amusingly, one of the letters was from everyone's favourite obscure force-field producer, Jared Corbo aka Radius! Which I find amusing. Very much so.