I thought I might throw in my two cents seeing as how I wait tables at a Brew pub out here in Oregon.
I'm tempted to wax all philosophical and go on a rant about how artisanal/craft produced food and drink should inspire the passions of all those who are involved with them, but I'll save that for some other time. Needless to say, however, if a bartender at a brewpub doesn't care about beer, he should move on to mixing margaritas at Chili's or some place like that. He would probably make more money anyway.
Fortunately, people here in Eugene seem to take their beer (and coffee, and cheese, bread, and food in general) very seriously. I like the fact the local barista will dump out 3 consecutive pulls until the crema on my espresso is just right. When people come into my pub, I make it my mission to show them something new whether they are homebrewers who have a taste for geuze (sp?) or budlight fans. I'm very liberal with pouring tasters; it makes my job easy and fun. Who doesn't like free beer. I just don't understand all the people who come to eat at our place, which has pretty pricey food, and just "don't care for beer."
1+ for leaving a small tip versus no tip. I have had people who have forgotten to leave a tip and get me back later, but in the meantime I'm usually wondering what I did to incur a customers anger.
1+ for letting your server/bartender know when something isn't to your liking, but in a non-hostile way. I've given free beers out for some ridiculous reasons: "my IPA is too hoppy" " the Orange Hef is too citrusy" etc. Just don't act like I tricked you into something you didn't like and don't sit there in silent judgement, waiting for me to figure out something's wrong.