Everybody loves an Irish accent, especially here in the U.S., but there isn't just one Irish accent. There are a number of different regional accents in Ireland, and if you develop an ear for them, you can tell pretty precisely where someone is from. From the mid-1990s until 2002, linguist Raymond Hickey traveled through all 32 counties of Ireland recording the voices of urban and rural speakers, of both genders, across three generations. They read from a set of sentences designed to target specific dialect features for purposes of comparison. You can listen to 15 samples, arranged on a map by origin, here.

To me, Donegal seems the best fit for our notion of ideal Irish, but they all have their charms. The Drogheda accent is so far from that ideal that if an American actor did an absolutely perfect rendition of it, he or she would only be laughed at for not getting "the Irish accent" right. Who knows, maybe there's a tiny, undiscovered hamlet where Justin Theroux's accent in Charlie's Angels: Full Throttle makes sense:

But I doubt it. "Teach us about pain," indeed.