Realistically, we often don’t have the means to check the theory ourselves.
And in a modern world where any and everything is marketed to death, we distrust the pro-speech.
But pragmatically, I find that quickly checking the con-speech is very effective.
If it has a point, it will make it clear.
If it is flaky, that was probably the best it could do.
(this does require resistance to fallacies and bullshit)
If people updated their belief towards those around them, then people with agendas would hammer loudly their forged belief at any opportunit… wait, isn’t this EXACTLY what they are doing ?