This article reports on Clean Language Interviewing (CLI), a rigorous, recently developed 'content-empty' (non-leading) approach to second-person interviewing in the science of consciousness. Also presented is a new systematic third-person method of validation that evaluates the questions and other verbal interventions by the interviewer to produce an adherence-to-method or 'cleanness' rating. A review of 19 interviews from five research studies provides a benchmark for interviewers seeking to minimize leading questions. The inter-rater reliability analysis demonstrates substantial agreement among raters with an (...) average intraclass correlation coefficient of 0.72 (95% CI). We propose that this method of validation is applicable not only to CLI but to second-person interviews more generally. (shrink)