Managers often accompany salespeople to customer meetings, and their presence can be invaluable to the interaction. However, at times, managers may act in ways that are harmful rather than helpful. Scant scholarly attention has been allocated to understanding the dark side of managerial involvement. When negative manager behaviors manifest in customer-facing situations, salespeople must understand and mitigate these occurrences to prevent deleterious outcomes. This study conducts a qualitative inquiry of professional salespeople and organizational buyers to uncover the ways customer-facing adverse manager behaviors (CFAMBs) occur and affect sales calls. Specifically, manifestations of manager arrogance, apathy, and awkwardness can negatively affect customer outcomes. In addition, factors affecting the severity of CFAMBs’ impact include timing in the sales cycle, customer status, and pre-, in-, and post-call mitigation strategies. Collectively, the findings advance role theory and theory germane to the salesperson–sales manager interface and provide practical guidance for dealing with CFAMBs.