I went to People and Groups and renamed a SharePoint Group from Fun-Together to "Fun Together" and went I went to Navigation and changed the Audience for a Navigation Heading (A document Library) in SharePoint 2013 Enterprise Edition SP1, it did NOT update the audience, it has a red underline. I had to update it by deleting it and adding the correct one "Fun Together." I do NOT think it is the spaces, I believe it is that it is different and audiences are not updating it. I don't know if a timerjob fixes this, but I noticed this after 5 minutes where I wanted to change the spelling.