You can usually discern fairly quickly when you are interacting with someone who is a conduit for someone else’s ideas and opinions; when they are a willing and empty vessel floating, self-satisfied, on an easy narrative stream that relieves them of the need to steer or navigate.
You can know because everything they say has been said, and could be said, by anyone on their particular side of the political spectrum. It is not a conversation so much as a choreographed performance of a fight, and it is pointless.
Ultimately, I really don’t care if we disagree, as long as your disagreement actually originates from your own mind and consists of points you actually thought of yourself. I value that. It’s increasingly rare.