I've seen it time and time again. People are less likely to notice bad reasoning when it's presented in an appealing package. Our thinking, no matter how clear, is liable to be swayed by whether or not we like the messenger.
Debates, you would think, are the epitome of rational thinking. But people don't follow arguments very well and instead focus on the personalities. I remember the audience responses to a debate between a Christian and an atheist. The audience was mostly Christians since they were members at the church that hosted the debate. A lot of the feedback to the question of who won the debate went like this: I know the Christian must have been right, but I think the atheist won because he was funnier. That's a pretty common response if the Christian doesn't work at being appealing rather than assuming the argument will sway the audience. I know the Christian in that debate, and he went on to become very intentional about improving his style. And he became more effective in debates.
I have watched clever videos that people ask us at STR to respond to. Sometimes the gulf between the premises and the conclusion is so obvious that I think it must be the fun video that was doing a lot of the persuasive work.
Look, this is natural. We're not purely rational creatures. Reason isn't the only thing that influences our thinking. What this points out is that to be effective ambassadors we have to have knowledge, wisdom, and character. We can't rely only on the soundness of our arguments. We have to be appealing messengers to commend the message.
That won't seal the deal either, but it will go a long way to being more persuasive.