This talk will look at how a trust model running on device A determines the extent to which A should initially trust device B in a given context (content category). It does so by considering two cases: in the first, A does not know B at all; in the second case, A knows B but in contexts other than that of interest. For each of those two cases, this talk will discuss the most recent proposal that improves on existing solutions (TRULLO and distributed propagation), and will also attempt to suggest new research directions (such as private collaborative filtering - post & more).