When I was potty training my dog, I made a big deal everytime she went outdoors. One day, she potty in the hallway. She was so proud that she kept running to me and back to her potty tail wagging excitedly. She expected me to give a 'good girl!' I just had to laugh. She equated my praise with pottying and not pottying outside.

The best investment I've made is getting a steam cleaner. Mix part pet odor with normal steam cleaning solution. Because once they potty in a certain spot, they'll keep going there.