In this articleIRBTMedianews Group/boston Herald Via Getty Images | Medianews Group | Getty ImagesLos Angeles resident Ruth Horne, 76, enticed by a bargain, bought what she thought was a Roomba to vacuum her house, but the experience ended in frustration."It kept getting stuck somewhere and would then just go around in circles," Horne said. She realized it was a cheaper knock-off. Meanwhile, Marcy Lewis, 75, of Madeira, Ohio, had been wanting a robot vacuum cleaner and deliberately chose a knock-off. "I'm p ...