The qualities and traits needed to be an effective ScrumMaster are difficult to catalogue and establish. What defines success as a ScrumMaster in one domain and for one set of teams does not always transfer into another domain for a different set of teams. However, one thing that has been clear to me in all my years of doing Scrum – if ScrumMaster is not 100% clear on their motivations for accepting the role, they will not be successful being the ScrumMaster.