Can one catch an alarming vibe about a potential psychopath despite their superficial charm?
Certainly, a key factor will be an inability to perceive emotional content beneath the veneer of superficial charm.
Psychopaths may mimic emotional cues but this may appear shallow and contrived.
A number of flags may display such as impulsivity and psychopaths are more easily bored requiring more drastic actions to stimulate interest.
Some research (Erlbaum 1995 as cited in Anderson and Kiehl 2017) showed a lower fear response in psychopaths.
There are many checklists available.
If one put enough attention and emotionally strong can easily identify a psychopath. Yes they are very charming but they often lie, don't care about other person safety, when in argument they try to gaslight and blame other for their mistakes, and most importantly they are Narcissistic.