In everyday life we are making decisions whose outcomes affect others. A friend may ask us for a favour, we might have business relations with some people etc. Every one of us has sometime felt betrayed by a friend that stopped creating that, up to that point successful, “chain” of mutual cooperation between us. There are people that we define as cheaters and others that we are sure that can be trusted. There are others that we trust and we are proved to be mistaken. Or people often try to gain the trust of others in order to delude them. Although society is supposed to be teaching the ethics of cooperation for centuries now, experience shows that deceit is very common in humanity either we like it or not. The reason is that deceit looks sweet.