I think you're right, Dani, but some girls will always do that in any situation--dress a notch above what the situation requires--and I don't know what can be done about that. I recall that many PNMs on GC have been advised to do just that!
Panhellenic can't win--if they don't publish a booklet, girls feel unprepared and gauche. If they do, some people dress up more than required and still leave PNMs feeling unprepared and gauche.