[postfacto]

Narcissists are very charming initially and very good at hiding it. Some tells:

- Very attuned to their own fashion attire. Very well/trendy dressed.

- Use the words/phrases “value”, “add value”

- Brag about themselves a lot. Talk about very lofty standards about very minor details.

[zozbot234]

>and very good at hiding it

Not really, you just need to know what to look for. A shallow, materialistic person with very little sense of humor, curiosity of the social/intellectual/cultural/creative kind, or visibly empathetic interest in others is a big red flag. The "curiosity" part may well be the easiest to assess as an observer, because it's not something that can be faked easily.

[proverbialbunny]

None of those criteria fits NPD, except that they're good at hiding it. Only a few kinds of narcissists are charming.