The more any one speaks of himself, the less he likes to hear another talked of.

Attention in a conversation is finite, and someone who spends it all on themselves has none left to give. You can watch it happen: the moment another name comes up, the self-absorbed listener goes flat, redirects, or waits visibly for their turn. It is not usually malice, just a small closed circuit that has never had reason to open.

Notice how you feel when a friend praises somebody else at length. If there is a flicker of impatience, treat that as a signal rather than a verdict, and ask them one genuine question about the person instead.