several years ago as I was playing fiddle at a session (here in Vancouver)
An Irish fellow (non-musician) who sat beside us mentioned that he enjoyed my playing, and said I had the East Clare style down quite well etc. But When he asked where I was from and found I wasn't Irish he said, so you're a Plastic Paddy then - And Id never heard the term but thought it was a bit pejorative. The implication is that you are a wannabe Irish, and that deep down, you really should be Irish to be playing Trad Irish music.
(And it obviously doesnt work the other way, as American Country Music seems to be hugely popular in Ireland, you turn on the radio and it Big Tom or such like while traditional Irish is far down on the list of popular music styles)
Still there is some resentment of foreign players, when I asked one of my (Irish) music friends (I use the term advisedly) about where to find good sessions in Ireland - he said (without apparent irony) you don't want to go to Doolin because that's where all the feckin' foreigners go....