Preventing trust erosion in design is often overlooked in favor of immediate revenue gains. A client struggled to articulate how avoiding a dark pattern could save long-term user trust, as the benefits of prevention are rarely reflected in quarterly reports. Interviews with 18 design leaders revealed that they are developing frameworks to measure trust, despite its intangible nature. The challenge lies in the “prevention paradox,” where successful prevention is often unrecognized until a catastrophe occurs, costing the company millions. Design leaders measure trust through several concrete methods. Customer satisfaction scores (CSAT/NPS) paired with support volume provide insights into user sentiment and potential issues. Task success rates track how well users complete critical tasks, revealing trust issues when abandonment rates rise. A qualitative-quantitative balance helps determine when to use exploratory research versus hard metrics. The AERC framework connects design decisions directly to business outcomes, such as acquisition and retention, while industry case studies offer proxy metrics for trust failures that haven’t occurred yet. Collaboration is essential. Partnerships with product managers, customer support, and data analytics teams help design leaders establish meaningful metrics. Understanding the business context is critical; attending meetings and engaging with stakeholders can sharpen insights. When data is limited, starting small with hypotheses can build initial buy-in. The article emphasizes that businesses often make trust-eroding decisions out of ignorance of the associated costs, but employing these measurement strategies can safeguard against such pitfalls.