The Tenali Rama and the three dolls

There was a great king called Krishna Deva Raya. One of his great ministers was Tenali Rama. Though extremely wise, he believed in teaching everything through fun. So he was called Vikata kavi- humorous poet
One day a wealth merchant came to the court of Krishna Deva Raya. He was from some other country. After saluting the king, he told, “Great king, People tell me that you have lot of wise ministers. If you permit me, I want to test them. “ The king became curious and agreed.
The merchant then gave the king three exactly similar looking dolls and told him, “Sir, these dolls look same but are different. Please ask your wise ministers to find out the difference. I would come back after 30 days. If none of you can find it, I will assume that you do not have any wise minister.” The king agreed and merchant went back.
Then the king called all his ministers except Tenali Rama and gave them each three days time to find out the difference between the dolls. None of them were able to find out. The king started getting worried. Then he called Tenali Rama. When Tenali Rama came, he gave the dolls told him, “Rama, I did not trouble earlier because I thought it must be very simple. But so far none of them have been able to find out the difference. I also tried and I was also not able to find out the difference. The pride of our country now depends on you.” Tenali Rama accepted the dolls and spent three days with the dolls. He was also finding it very difficult. But at last he found out.
Next day, he went to the court. The merchant also came that day. Then Tenali Rama told him, “These dolls are different. One is very good, another medium and another bad.” The merchant, the king and all other ministers asked, “Which is which?”
Then Tenali Rama showed them a tiny hole in the ears of the dolls. He took the first doll and put a very thin wire through this hole. The wire came out of the doll’s mouth. For the next doll, the wire came out of its other ear. For the third doll, the wire went to his heart and never came out. Tenali Rama told, “The first doll, where the wire came out of its mouth is bad. It represents people, to whom, if we tell a secret, they will tell it to others. The second doll, where the wire came out of the other ear, represents people who do not understand what you say. They are harmless and are medium. Tin case of the third, the secret goes to the heart and is preserved there.”
The merchant and the king were pleased by Tenali Raman’s finding and gave him lot of presents. Then Tenali Rama told them that his explanation was wrong .He told them, “There is another explanation. The fist doll represents people who hear and teach it to others. So they are good. The second doll represents people who hear and do not understand. So they are medium. The third type of people are those who learn things and do not teach it to any body and keep everything secret. They are bad people.” Then the king asked, “Is there any other explanation?” Can you reply him?