In the field of trust and reputation systems research, there is a need for common and more mature evaluation metrics for the purpose of producing meaningful comparisons of system proposals. In the state of the art, evaluations are based on simulated comparisons of how quickly negative reputation reports spread in the network or which decision policy gains more points against others in a specific gamelike setting, for example. We propose a next step in identifying criteria for a maturity model on the behavioural analysis of reputation-based trust systems.