"He's Such A Great Guy"... "She's Such A Peach"

Classic "Narcissists" are often the one in the group who everyone talks about being so energetic, so wonderful, so helpful, so 'brilliant', or so responsible.
These kinds of personalities DO exist, but look around the person; how are the people close to them doing? Partner, family, friends.

In person, when they are with their partner, "close friend", or older child, do they seem like "Peas and Carrots", or do they seem more like a Charismatic celebrity and an "Assistant" who is expected to stand back in the shadows?
(Do you go along with it and ignore the supposedly "shy one", or are you equally polite and courteous to BOTH of them?)

How are all of their kids doing? Not just the one who everyone praises, but all of them?
Do they include their kids in their plans, in their activities, or do they consistently leave them out? How much do they actually support their kids emotionally and in their endeavors? Is only one of them doing well?
How do they talk about their kids, or their siblings, or other relatives; do they sound neutral or positive? Or do they seem to be painting a picture of their own child or other relatives as "Losers"? (It's not the same thing as speaking in confidence about abuse, or seeking support for difficult relationships or situations; not even close.)
When they "brag" about their adult kids, are they bragging about their actual child, or are they bragging about their child's SPOUSE?
How is their own spouse? Does he or she seem exuberant, confident, and loved? Do they include their partner in their activities? Or does the "partner" get left on the "sidelines", like an audience member, a servant, or an "outsider"?
If they both have a "Facebook" or other social media, can you tell by the posts on BOTH of their pages that they support one another, or does only one of them seem to be supportive of the other?
Does one of them look very young, and the other seems to be rapidly aging, old for their years? (Especially in the case of parents and adult children.)
Do they frequently brag about themselves, their endeavors, people they know, what they had for breakfast?
Do they often imply that others in their personal lives are failures, or that others in their family are just not "responsible enough", and that's why they have hardship?

We don't REALLY know the people around us; we humans tend to make a lot of assumptions based on very little information, and based on our own feelings.
This person makes ME FEEL GOOD, so therefore I will agree that they're a "good person".
This other person makes me FEEL a little bit uncomfortable for whatever reason, so I will go along with the others treating them with less respect, or even with disrespect.

This human tendency to assume, and to go along with others, is one of the main reasons Narcissists GET control of both small and large groups, and KEEP control.

Narcissists literally USE the energy of others to keep their motors clean and shiny, so they are often the most "charged up" members of any group that they're in. They also stand on the backs of others to get a higher position, and to stay ABOVE everyone else.