Yes yes Alia is fremen and they don't wear panties. But once she become the Regent she suddenly has a ton of AMAZING outfits, so i pictures her have a whole stash of stuff like this:
(http://s238.photobucket.com/albums/ff233/teacuplolita/?action=view&current=aliaundies.jpg)
(no matter how hard you look I promise you her girl bits are covered I used to sell this stull they air brush the crap out of the photos so nothing can show!)

But she makes Duncan wear this: (scantily clothed man warning!! but he is covered!) http://i238.photobucket.com/albums/ff233/teacuplolita/ducanpanties.jpg