“…The literature on survey non-response is well-developed (for a recent overview, see Bach et al, 2020), and many studies have analysed the processes of selection and recruitment, and reluctance, in ethnographic research, especially focusing on the complex issue of access (Bengry-Howell and Griffin, 2012; Riese, 2019). With some relevant exception, instead, methodological literature often overlooks the problems arising in the process of recruiting participants for interview-based research (Adler and Adler, 2003; Anthony and Danaher, 2016; Clark, 2010; Emmel, 2014; Kristensen and Ravn, 2015; Levine, 2017; McCormack et al, 2012; Reybold et al, 2012). However, the interest is increasing in recent years, especially in case of vulnerable or hard-to-reach populations, even though both ‘vulnerable’ (Aldridge, 2004) and ‘hard-to-reach’ (Marpsat and Razafindratsima, 2010) statuses are complex to define 2 .…”