Well like I said, there's rampant racism here, but you'll find it mostly confined to a) talk, mostly in pubs and b) drunken louts at night who decide to pick on someone. So like, a Pole or a Romanian could walk down any street in Dublin without fear (maybe not at night, but that wouldn't be anything to do with his nationality; Dublin is not a safe place at night in some areas no matter who you are) and generally people don't try to segregate or separate them. To be honest, for about 95% of Irish people, anyone coming into Ireland just after a while becomes accepted as Irish. It's really funny to see a Chinese guy or an African woman speak with a thick Dublin accent!
Like I say, as long as you can stand your round you're all right by us. There are the minority idiots just looking for a fight of course, but sure you'll get them anywhere. And old people; old people are hugely intolerant of "foreign fellas", but then, they come from a different generation. Not that it makes it right or anything but you can see where they have a different worldview than my generation do.