We started having dress checks in the past year just to make sure everyone was on target with the theme. There were several more "difficult" sisters who tried to rebel and would purposely not wear something within the theme that was designated. It's also good to make sure clothes fit correctly and are comfortable. Also, it's a showcase for things you may want to borrow from someone else
It's basically just a check to make sure everything's okay, and it's not a big event. Basicall done before or after another event, and its not parading in front of everyone, just mainly checking with the rush chair and her assistants.
It's worked well for us.