Possible Clues:

• Locks securing books, nothing worth listening to
• Bombast makes tax officer retire in shock
• "I'm Too Sexy" or "Summer in the City"?
• Bombastic talk or balloon elevator
• Empty talk? It helped the Montgolfiers
• Empty talk over the Sahara?
• Just talk, nothing more
• Meaningless verbiage
• A lot of campaign rhetoric
• ___ balloon