The necessary cooperation in packet forwarding by wireless mobile ad hoc network users can be achieved if nodes create a distributed cooperation enforcement mechanism. One of the most significant roles in this mechanism is played by a trust system, which enables forwarding nodes to distinguish between cooperative (therefore trustworthy) and selfish (untrustworthy) nodes. As shown in this paper, the performance of the system depends on the data classes describing the forwarding behaviour of nodes, which are used for the evaluation of their level of cooperation. The paper demonstrates that partition of such data into personal and general classes can help to create better protection against clique-building among nodes. Personal data takes into account the status of packets originated by a node itself, while general considers the status of packets originated by other nodes. Computational experiments demonstrate that, in the presence of a large number of selfish and colluding nodes, prioritising the personal data improves the performance of cooperative nodes and creates a better defence against colluding free-riders.