You guys are giving me some hope here-- Penny's still under two, and with people talking about taking several years for their dogs to "get it", maybe we'll still do it. 

  98% is soooo close to 100%... 
I feel like she was at a disadvantage where housebreaking was concerned. She spent the first 5 months of her life-- prime training time for most pups-- with a byb-turned-pet hoarder who just let all her dogs run about the house and urinate or defecate wherever they wanted, and never cleaned it up.  It was really a terrible situation, and I'm sure that spending her youth in that mess influenced Pen's opinion of where it is appropriate to do her business. 
I just try to keep calm and tell myself that it really isn't her fault, and that there are more important things in the world than a pristine carpet.