The rise of "social acceptability" as an inevitable - somewhat embarrassing - dimension in the assessment of technological projects should not be regarded as a temporary occurrence, related to occasional governance deficits. In this paper, we take it as a structural phenomenon and relate it to the inevitable trials that socio-technical devices face in their emergence – i.e. the process of their assemblage - and after. Accordingly, we propose to distinguish between the "issue" and the "problem" of acceptability. The former refers to a condition that is inherent to the assemblage of any socio-technical device and has been well analyzed by the sociology of science and technology, the latter points at a specific configuration in which the issue takes on a public dimension and a public mode of regulation. Stepping back to the sociological analysis of the assemblage of socio-technical devices - the "issue" of acceptability - allows us to regard the "problem" of acceptability as a trial aimed at re-opening this assemblage. We rely on available empirical material in order to describe the contours and the dynamics of acceptability trials as well as their potential effects. We show that the usages of the term "acceptability" in these trials convey problematic framings and that the outcomes of these trials remain fundamentally ambivalent. As far as social sciences are concerned, these elements call for prudence in our engagement. Describing the ‘problem’ of acceptability as a trial allows us to derive some guiding criteria for a cautious engagement.