I have an old-ish songbook from the 1930s. It has some songs with cod-plantation accents - fake black. Sort of Swanee River ("ribber") but worse. My "native" accent is a nasal English public (i.e. private) school with a hint of Australian from the 3 years I lived there. Now surely it would be just anathema for me to "black up" my voice to sing those songs. Wouldn't it?

And could I not expect someone from Ireland (as distinct from Northern Ireland or Ulster according to you preference) to object if were to do "The Old alarm Clock" in a fake Irish accent?