there's huge differences between one place and another. You can get a 'good' Guinness anywhere, even California, its just more rare. And this isnt my interpretation of 'good' There are rules that Guinness have, and even contests that follow the rules to see the best poured pint. But the differences between bars near the arena, are like you said, turnover (huge difference), and storage temperature, and also the lines from the kegs to the taps, but most importantly, from one bar to the next, is how its poured. Some bars teach their bartenders to pour correctly, some bars have them pour it as quickly as possible.