Application-Level Multicast (ALM) has been proposed as an alternative solution to overcome the lack of deployment of the IP Multicast group communication model. It builds an overlay tree consisting of end-to-end unicast connections between end-hosts based on the collaboration of group members with each other. The efficiency of the constructed overlay tree depends entirely on the honesty and on the cooperation of all participating members. However such behaviour can not be guaranteed and some selfish and non-cooperative nodes may take profit from the honesty of other members in the overlay. Recently, many researchers have been investigating the impact of selfishness of nodes in the overlay multicast. Our contribution in this paper is to describe in detail the basic algorithms used to construct the overlay tree, and evaluate the impact of cheating nodes on the stability and on the performance of constructed overlay tree using these algorithms.