Depends where you are. Are you really going to nurse a beer for 3 hours? Kinda gets piss warm...doesn't it? No bartender will throw you out, they'll just give you dirty looks if you ain't tipping them or they won't serve you at all. Better to tip, than not cause money talks. Besides there is STILL people who still get drinks and don't tip. I rather serve someone who might be sitting at the bar all night and tip versus someone else who doesn't.