For the most part, the American gypsies who do the crap driveways, roof repair, etc are Irish Travelers (Irish-American decent). Running all the way from northern New York down the East coast (usually). The women are big on shoplifting and some money/lotto con games. Travelers are very fond of the "Spanish Prisoner" con game. Will winter in Florida or Georgia mostly. They travel in caravans together; motor homes, campers, etc. Work a lot of swap meets and junk yards.
Strong family clans within the Travelers. Inter marriage, between clans, with kid as young as 12. Monarchy style of structure among the Travelers. Not too much in SoCal, though the winter/rainy season brings some out. Mexican style gypsies increasing lately.Prone to more strong arm stuff.
Got most of this information from a friend who works with the Riverside county DA's office. He's Irish-American and tends to get a little pissed about the Irish Travelers.