This paper addresses the issue of maintaining information coherence and its robustness in a multi-agent system, that collectively gathers information from distributed sources and where some sources may be defective (deliberately or not). In this context, the collective information gathered by the system is a progressive (non linear) aggregation of information collected individually by each agent. Therefore, each agent has direct information (collected by itself) and indirect information (obtained through communication with other agents). System coherence is defined by compatibility of collected information about the explored environment with actual information of the environment. System resilience is defined by the capability to maintain information coherence, despite the existence and increase of faulty agents within the system. In this context, we propose a new trust-based mechanism to detect defective agents and limit the dissemination of deceitful information in the system, thus reducing its impact on the process of collective information gathering.