About a month ago at our curling club I asked for a pint of something or the other (light ale or lager; they don't have much for selection), when they brought it out it had ZERO carbonation. So I took it back up to the bar and told the cougar bartender their beer was flat. She said "What do you mean?" I said "Well, beer is supposed to have bubbles in it, right? Do you see any bubbles here?" She retorted "Well, I haven't had any other complaints." So I pressed her: "But you agree beer is supposed to be carbonated? Just give me a bottle of (whatever it was) please." And she did.
It's getting to the point where the number of places out where I can have a pint is growing limited. Many places beer is being poured/served by people who have no idea about the importance of proper CO2, cleanliness of lines, etc. They turn the gas way down to make it easy to pour, but if you're not turning over enough volume, all of a sudden your beer is flat. And it's horrifying to think about the places that never, ever clean their lines. But if you say anything or send your beer back you're a problem customer. I've often thought in a big enough city you could have a nice business cleaning lines for places with beer on tap.