If you want it to be intelligible to the listener than sing it sober. The Irish have been stereotyped for so long as victims of the "Irish Curse" that it make sense for this to be reversed. The cartoon of the fighting and drinking Irishman has been another form of
cultural stereotyping as bad as the watermelon eating "negro".

I would personally prefer to hear Irish songs sung sober as they are generally better sung
this way with nicer voices. The bawling ranting voice of an alcoholic bar room singer has become an irritant in the dissemination of Irish music.

Frank