I reckon nicknames were fairly common among the Irish in the 19th century . Sharon provided a link to a great list of nicknames used by the Irish of Buffalo, New York in the 1800's. The listing includes a "Dirty Shirt" McGee:
http://www.ourlibrary.ca/phpbb2/viewtopic.php?t=6948
But the nicknames for most people would have not been recorded and are unfortunately lost in time. The Irish and British newspapers appear far more formal than American newspapers, so we don't learn of many nicknames. Michael Considine frequently got his name in the newspaper, but we never see him being referred to as "Dirty Mick" in the newspapers during his lifetime. We only learn of his nickname through "The Disturbed Clare" by Bernard Becker in 1880. Michael Considine was given this special treatment by Becker since he was such a popular man in Ennis.
Aside from the allegations of embezzlement of funds for the O'Connell Monument, and the fact that Michael Considine was a well-known political figure during a time of corrupt politics, I get the sense that "Dirty Mick" was in reference to corruption based on how he was typically referred to in the press. At the start of the fundraising campaign for the O'Connell Monument in 1859, Michael Considine when presented with a purse of gold from his friends and admirers (an easy method of money laundering embezzled funds?), he was described as having "incorruptible integrity." In Father Vaughan's letter of December 1864 to John Martin, Michael Considine was described as "earnest and honest" as well as "that incorruptible man". Did his admirers feel the need to describe Michael Considine as "incorruptible" since he was more well known in County Clare as "Dirty Mick", a nickname alluding to corruption?
Michael Considine was very popular in Ennis and I reckon the nickname "Dirty Mick" was used among his friends and supporters. There may have even been an added joke to the name. A "Dirty Mick" in America was a derogatory term for an Irishman or a Catholic. It must date back to the 1850's, when America was very anti-Irish and the Know Nothing movement was strong. The Irish were likely aware of its use in America back in the day. Frequently negative terms are adopted by those being ridiculed and this could have been the case for Michael Considine's nickname. A great example of this is with the negative stereotype of the Irish as always angry and fighting. The University of Notre Dame adopted "The Fighting Irish" for their nickname as well as leprechaun mascot, who like Michael Considine wears a green suit: I reckon most Americans today would not be familiar with the term "Dirty Mick". The below newspaper's letter to the editor is a good example of its use and the continued anti-Irish prejudice well into the 20th century. It was written just one week shy of 100 years ago, but still sounds oddly familiar:
** Sheila, please allow me just a quick historical footnote since it has a likely County Clare connection. It might be surprising that the Los Angeles Times would print such a letter in 1919, but it was a very conservative newspaper 100 years ago. Its owners, the Otis and Chandler families, were very anti-union which made them a target for socialists and anarchists. On the 1st of October of 1910, the Los Angeles Times building was blown up killing 20 employees of the newspaper. Two brothers, James B McNamara and John J McNamara, members of the Iron Workers Union, were found guilty of the crime. They were defended by the lawyer Clarence Darrow (famous for the Scopes "Monkey" Trial). The McNamara trial was known as the "trial of the century" which certainly makes researching the surname McNamara difficult in newspaper archives starting in 1910.Time to Wake Up.
GARDENA, Oct. 13 - [To the Editor of The Times:] Don't you think it is about time for the American people to wake up? Are we going to have this country run by Americans or by a bunch of "Irish Micks?" It is getting so that a decent man cannot work and make a living for himself and family without some dirty "Mick" trying to beat him up. I noticed in today's Times where an American at the harbor was attacked by two "Micks" and a Mexican. It seems that he fought back and struck all three with a knife. Well, he did just right! I wish we had a few more like him. My ancestors fought in the French and Indian wars. Another was a captain in the war of 1776. His son was a captain in the war of 1812, my grandfather, a Yankee soldier was killed in the Civil War. Look at the names of the strike leaders. Nine out of every ten are "Mick." Who blew up The Times Building?** What is Mooney? The answer to all of this is they are "Micks." But what are we going to do about it? President Wilson has a "Mick" as a private secretary. Mrs. Wilson while on a trip to France had "Micks" exclusively as her ladies in waiting, appointed by the Knights of Columbus. When the Legislature of this country declares in favor of home rule in Ireland it is enough to make any decent American almost ashamed of his country. I have noticed The Times always prints the news regardless of whose toes it hurts and I am sending this in with the hope that it gets before the American people. Let us try and keep this land what its founders intended it should be.
ETHAN ALLEN REID.
Los Angeles Times, 16 October 1919
Highly recommend the book "American Lightning" by Howard Blum if interested in this case. Although the book doesn't research the likely County Clare ancestry of the McNamara family which is a bit disappointing.
Here is John J McNamara (age 33; a laborer, "Structural Iron Work") boarding in Indianapolis, Indiana in the 1910 Census - only six months prior to the bombing:
https://www.familysearch.org/ark:/61903/1:1:MKP5-KJC
And his Irish born widowed mother, Mary Teresa McNamara (maiden name Donlan or Doolan?) and children including James B McNamara (age 26) living in Cincinnati, Ohio in 1910. I believe their Irish born father John A McNamara (born 1849) died sometime between 1900 and 1910:
https://www.familysearch.org/ark:/61903/1:1:ML8S-D6M