Through insights obtained from an ethnography of face-to-face survey data collection in the UK, this article examines the under-explored role of the survey interviewer, documenting the how and why of interviewer effects as they occur in practice. It highlights the emotional labour required to perform the role, and the ways in which interviewers handle challenging interpersonal scenarios during data collection stemming from the idiosyncrasies of respondent concerns alongside questionnaire design issues. It offers sociological commentary on the typical working conditions of professional survey interviewers and calls for a re-evaluation of the role of survey interviewers, both to recognise their important role, and for survey designers (and therefore survey data) to benefit from their insights into sources of survey error.