Few things damage the trust of parents of ADHD children as quickly or deeply as habitual lying. I don't mean the little white lies that everyone tells once in a while, but repeated lying that causes conflicts and difficulties.
Some ADHD kids may not be dishonest as much as they are victims of uncontrolled ADHD symptoms. Barry's mother, for example, tells him to come right home after school, because the family is going out to dinner. Distracted and rushing, he mumbles, "Yeah, OK, Mom." In the course of a hectic day, he forgets his mother's reminder and walks in an hour late. When his parents confront him, Barry stubbornly argues that his mom never told him to be home early. Is he lying? No, he forgot. It is an organization and record-keeping issue, not an honesty issue.