...overnight? I had an open tab and came the next day to pick it up, to find out they closed it, put a 20% tip on my behalf, with "THANX!" as the signature. Yeah, you welcome.
There's nothing outstanding about that amount, but isn't the tip supposed to be the costumer's decision, depending on service? People tend to come back for their credit cards... why not wait for them to close the tab?
Well any time you give your credit card to a waiter etc. it's an opportunity for identity theft... I do use cash in 99% of the time when I go to bars.

tip is your decision, unless it is already included in the bill, if i were you i wouldn't allow them to make any charges for you again.. what will stop them from charging as much as they want the next time??

tip is your decision, unless it is already included in the bill, if i were you i wouldn't allow them to make any charges for you again.. what will stop them from charging as much as they want the next time??

I never had an open tab, but it sounds like an easy way for identity theft!