Then, playing by their rules, you pay with a credit card and walk away with your coffee and they see the back of your shirt says, "Will not honor credit card bills."
Nah, I'll call them a dickhead for illegally using the wifi logo. It's trademarked by the Wifi Alliance, the group that establishes and sets the standards for wifi, as well as conducts interoperability testing and issues compliance certification. The use of the logo without certification or permission is a trademark violation.
That's the evilest thing I can imagine