This 18% thing is new to me. I always thought it was 15% and that is usually the minimum of what I would tip (bad service or no). I've never really gotten bad service.. or service I consider so bad to not deserve some sort of tip because I am still being served even if not as well as the next guy.
Waiters/waitresses are the whipping boys and girls of the restaurant industry because they are the ones the customer sees imo.
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lol @ Vega. You remind me of Mr. Pink in Reservoir Dogs.