Wait what?
Are you doing this on Horde side or Alliance side? I have literally never had anyone not invite me even on fresh 100s and never had any issue getting the password. Either the pw is already in people's comments or I go in and just say "What's the password" and about 5 people give it out.
I have also never been in a channel where anyone was not invited or complained about not getting invited and I've geared 6 different characters to ilvl 700 or thereabouts with these Ashrans.
What exactly are you doing?
EDIT: The only problem I've ever had is that the people are gigantic fucking dorks and it can be painful listening to them have conversations in vent.