Fine words and an insinuating appearance are seldom associated with true virtue.

Charm is cheap to produce and expensive to verify, which is why it correlates so poorly with reliability. Someone very good at the presentation has usually invested in the presentation, and that investment has to come from somewhere. It is not a rule, since plenty of decent people are also charming, but smoothness is not evidence and it gets mistaken for evidence constantly.

Judge on the record rather than the delivery. Ask what the person has actually done over time, particularly when it was inconvenient and nobody would have known.