We have used disinfectant, Simple Green and some powerful cleaner that is used dog kennels. The powerful cleaner did do a good job first time at killing smell and for about 2 days he stopped pooing in the area completely. Now it does not seem to work as well, plus it has big poison warnings, so I am a bit concerned with what it is doing to the environment.

Have not tried vinegar yet, need to buy myself a more.