The “smoothness” or social facility psychopaths display is generally not matched by congruent and concomitant emotion. They may have a very easy “way with words” (sometimes accompanied by equally charming nonverbal gestures), but usually their smooth talk is not accompanied by any emotion that matches what they’re saying or that can be sensed and felt by others as genuine.
Some folks are charming in the most benign and appealing way. They are not only sincerely well-mannered but also genuinely positively regarding of others. The very way in which they conduct themselves and the authentic respect they have for others is “attractive” in its own right. But there are those characters whose display of charm is a farce, part of a calculated use of seduction to take advantage of others.