Behind its never-ending feel-good marketing campaigns, AARP, formerly known as the American Association of Retired Persons, is a multi-billion-dollar organization that spends millions lobbying Congress and state legislatures — making the organization an influence-peddling powerhouse. Though the group boasts 38 million senior citizens as its members, it’s not clear how many of its positions benefit America’s retirees. But AARP certainly serves as a useful lobbying arm for the health-insurance industry, particularly health conglomerate UnitedHealth.