In the u. s., irish male immigrants used to be perceived as
violent.
hard-working.
intelligent.
moral.

The answer is violent.  This was because of the negative impression that began in the medieval period to the present.  To support the claim of King Henry II to invade Ireland, a Norman chronicler known as Gerard of Wales wrote many derogatory remarks against the Irish and this caught on.  It got worse as time went by and the Irish people were oppressed under British rule.  Even when they decided to travel to America, they were viewed as a rowdy and violent people.  Although public perception of them has changed, they still are seen in a negative light.