One thing a barperson can do while pouring Guinness is to move it under the tap so as to draw a
shamrock. (I have also seen someone do a
harp because it amused her artistic sensibilities, but a shamrock is the traditional device.) If this is begun when the Guinness is half poured, it should continue in existence as the rest of the glass is slowly filled, and
stay there. The froth is firm.
Guinness's advertisements have been famous for imagination; I shan't condone advertising by describing them, however. I suppose it's safe to say that one from many decades ago featured a toucan, I'm not sure why. They also touted the notion of physical strength (the kind that allows you to lift iron girders, that is).
The old slogan was "Guinness is Good for You". They probably can't get away with this now, but it certainly is quite nutritive. When I've been on benders involving lots of alcohol but no food for more than 24 hours, the only way I could have survived it was by having plenty of Guinness amid my other drinks. More seasoned drinkers than me have said they've gone for a week living on it. I believe them. The story is that nursing mothers used to be given a bottle of Guinness to get their strength back up after the ordeal. Whether the iron and B-group vitamins in it are as nutritious as their legendary reputation has them, I leave to others.
I don't much like ordinary Guinness. (Nor Beamish nor Murphy, neither of which seems an interesting alternative.) One St Patrick's Day my local was giving it away free. I arrived early and had a couple, but it's too weak for my taste, and bland, and I went back to buying proper beer.
A different matter is Guinness Foreign Extra, a vastly stronger drink (at 7.5%), sold in bottles, and formerly not sold here in Britain at all. It was intended for export to tropical climes, or was locally brewed in places like Nigeria and Trinidad. (Could U2 have been drinking that, and not draught Guinness?) It's black, it's nutrient-rich, it has a sharp, bitter iron taste, with a huge amount of body. The back of the bottle is utterly useless for explaining it. Anyway, it's an entirely different drink from the weak stuff that's served in pubs, and I grab it all whenever I see it.