Why does Guiness taste better in Ireland than it does in the US?
Oh, the memories...................
Was in Wales back in '84. Holyhead, to be exact. On a Scuba expedition.
In the evenings we would drink Guiness and also question why it was so good. So we asked Cliff who worked at the dive center (centre, for our UK audience).
"The Guiness get's better the closer you get to Ireland!", he exclaimed.
One day while out diving from a raft (inflatable, for our UK audience) out in the Irish Sea, we note a Sea Link Ferry sailing from Wales to Ireland in the distance. Cliff then points out: "Gentlemen, there is your chance to experience true Guiness."
The Sea Link (or Sea Stink, according to the locals) ferry provided an excellent method to partake in the fine art of Guiness familiarization. Short trip over and back. All the while indulging in beer, women and song. Personally, I don't remember too much about Ireland on that brief visit during the summer of 1984. Hell, I don't even recall much about that particular trip from Wales to Ireland. The beer on the boat was fantastic. The Guiness was certainly beautiful in Ireland.
Preservatives probably is the reason for the taste. And the fact that the Guiness imported here to the USA is a tad bit aged and not as fresh when consumed over here. Personally, I prefer Guiness from the tap. I wish I could fully answer your question. However, some of the finer things in life are best left unanswered.