The online ads promised free trials of acai berry weight-loss and colon-cleansing pills. And they offered celebrity endorsements from Oprah Winfrey and TV chef Rachael Ray .It was all a scam, according to the Federal Trade Commission . The free trials ended up costing consumers plenty, for continued shipments of pills they didn't want, with bills for $45 to $65 each time. And neither Winfrey ...