I tried to make the point that dogs don't see poo as disgusting, they see it as a message from another dog - she knows where she put her poo so there is no point showing her where she did it.
She will not connect the fact that it is her poo to the fact that you are un happy UNLESS you catch her in the act of DOING it. There is no way it is possible for her to connect you telling her off while showing her the mess to the act of her making the mess. Dogs quite simply do not work that way.
She learned the house training because you took her out frequently and praised her when she went in the right place.

Obedience trainers do not always know about behaviour, as your trainer has proved! They have learned a system of training that works for the majority of animals. If asked, many will tell you that a dog learns because when it does the right thing it is praised and when it does the wrong thing it is punished. Dogs do learn some things in this way but this is not showing any understanding of behaviour. It is retelling what they have been told. Why would the dog want to do it the right way? Why would the dog get it wrong? When is it fair to correct and for what reason? How can you use body language and natural responses to help the dog?
When a trainer is telling you to house train your dog with the method you used and then manages to convince you that it worked they appear to be very good. They clearly have no understanding of canine psychology or basic behaviour.