I haven't been in Ireland but all the people i know who been there told me the same...it's because they don't mix the beer with too much water and that the water they do use taste differently.
I've been in Amsterdam 4 years ago and my beloved Heiny tasted so much better there than in Israel...they say the beer gets its special taste from the water from the canals(where all the floating houses flush their toilets to)
Leffe tasted differently in Belguim too