WASHINGTON -- TV ads show smiling seniors enjoying an "active" lifestyle on a motorized scooter, taking in the sights at the Grand Canyon, fishing on a pier and high-fiving their grandchildren at a baseball game.The commercials, which promise independence to people with limited mobility, have driven the nearly $1 billion U.S. market for power wheelchairs and scooters. But the spots by the industry's two leading companies, the Scooter Store and Hoveround, have also drawn scrutiny from doctors and lawmakers who say the ads make seniors think they need a scooter to get around when many don't.Members of Congress say the ads lead to hundreds of millions of dollars in unnecessary spending by Medicare, which is supposed to pay for scooters only as a medical necessity when seniors cannot use a cane, a walker or a regular wheelchair.Government inspectors say up to 80 percent of the scooters and power wheelchairs bought by Medicare go to people who don't meet the requirements. And doctors say more than money is at stake: Seniors who use scooters unnecessarily can become sedentary, making obesity and other disorders worse."Patients have been brainwashed by the Scooter Store," said Dr. Barbara Messinger-Rapport, director of geriatric medicine at the Cleveland Clinic. "What they're implying is that you can use these scooters to leave the house, to socialize, to get to bingo."The scooter controversy, which has escalated with a raid by federal authorities on the Scooter Store's New Braunfels headquarters last month, underscores the influence TV ads can have on medical decisions.Like their peers in the drug industry, scooter companies say direct-to-consumer advertising educates patients about their medical options. But critics argue that the scooter spots are little more than sales pitches that cause patients to pressure doctors to prescribe unnecessary equipment.The Scooter Store and Hoveround, both privately held companies that together make up about 70 percent of the U.S. market for scooters, spent more than $180 million on TV, radio and print advertising in 2011, up 20 percent from 2008, according to advertising tracker Kantar Media. Their ads often include language that the scooters can be paid for by Medicare or other insurance: "Nine out of 10 people got them for little or no cost," one Hoveround ad states.Hoveround did not respond to a half-dozen requests for comment. The Scooter Store, the nation's biggest seller of scooters, said most people who contact the company after seeing the ads do not ultimately receive a scooter."The fact that 87 percent of the persons who seek power mobility products from the Scooter Store under their Medicare benefits are disqualified by the company's screening process is powerful evidence of the company's commitment to ensuring that only legitimate claims are submitted to Medicare," the company said in a statement.The Scooter Store has operated with a streamlined staff in recent days because of massive layoffs after the federal raid.Allegations of Medicare fraud in the industry go back nearly a decade.In 2005, the Justice Department sued the Scooter Store, alleging that its advertising enticed seniors to obtain power scooters provided by Medicare and that the company then sold patients more expensive scooters that they did not want or need. The Scooter Store settled that case in 2007 for $4 million.In 2011, government auditors estimated that the Scooter Store received $47 million to $88 million in improper payments.