My 5 year old husky, who was house trained, decided that the foam floor in the home gym I built didn't count as off limits for doing her business. I watched her for about 3 weeks, and I noticed she didn't go in there for any other reason, so I set a motion detector which triggered a wav file of me sayin "bad girl shadow!" or something similar (I can't really remember now) over the speakers in the gym, which ran whenever she was home alone. She stopped immediately and after about 6 weeks I took the motion detector to use somewhere else and we've had no more problems...
