Originally Posted by
WonderDude
One of the "important tips" from the guide warns that restaurants typically obtain authorization to charge 20% more than your actual bill when they first swipe any plastic, so that they know you've got enough credit line to cover the tip.
I get SMS messages from my banks in seconds, even before receipts are printed. I have never seen these additions and I will never sign such receipts. If I ever see such scam, they will get zero tips.