It normally is pretty simple to convince them of the geographic name. If they have a sponsor name in their event name, I let them know that I will charge them to change the name if they get another sponsor.
I now can point to the naming rights for Mile High Stadium in Denver - it started as "Invesco Field" when it was built, then changed to "Sports Authority Field". Sports Authority has filed for liquidation bankruptcy, so the name will likely change, again.