Well, to the Ancient Order of Hibernians, I assure you the wearing of orange on Paddy's Day would most definitely be perceived as a bigoted affront, because of it's association with Ireland's Orange Order, whom they (the AOH) perceive as the Northern Irish equivalent of the KKK.

Most Irish Catholics will also blanch at someone wearing orange on St Paddy's Day.

I think here in the Twin Cities, where a lot of Scandinavian Lutherans grew up "across the river" from St. Paul, which was a more Catholic city, it is simply a holdover of anti-Catholic bigotry. That is how the Scandinavian Lutheran librarian phrased it. She claimed it was to show they didn't worship the pope.

I think anywhere you see a lot of political and economic competition between Protestants and Catholics, you see the phenomenon of orange on the day. And also in places where there is a large contingency of Irish Protestants who feel threatened by the ascendancy of Irish Catholic identity/nadir of WASP dominance around the world in the more recent past.