It helps if you go to the same bar (the bartender knows you) or you tip accordingly. If you just go to a random bar and just ask for a bottle, chances are you will be charged. I saw this on the Liberty first hand last week. A random person walked up to the bar and asked for two bottles. The bartender charged for the two. I asked the bartender why he didn't change me for the same. His answer was, I know you and you take care of me.