Shady practices keep illegal immigrants off books and tax rolls, without health coverage. Introduce one kind of lawbreaking to the workplace — immigrants on the job illegally — and other cheating follows. The result swindles workers, the government or both. Businesspeople, unions and immigrants list a variety of tricks used to game the system. Such tactics aren’t exclusive to job sites with immigrants in the country illegally. But the use of an illicit work force sets the tone, and can offer easier opportunity because workers here illegally — with poor English, little education, vulnerable to deportation — stand particularly vulnerable...