My view is that for anything reasonably consequential (ie potentially worth the time spent investigating), one should at least briefly probe before deferring as a) virtually everyone lies at least occasionally and b) popular opinions are often clearly dubious due to the inertia they carry within a group (even a group of experts) from other people deferring without investigating (this can result in evidence needing to be overwhelming to shift majority opinion and overcome this self-perpetuating cycle).
My view is that for anything reasonably consequential (ie potentially worth the time spent investigating), one should at least briefly probe before deferring as a) virtually everyone lies at least occasionally and b) popular opinions are often clearly dubious due to the inertia they carry within a group (even a group of experts) from other people deferring without investigating (this can result in evidence needing to be overwhelming to shift majority opinion and overcome this self-perpetuating cycle).