I think this depends strongly on whether the person you're explaining-to is initially open or closed to your ideas.

An example - if a new-earth creationist approached me to talk about their ideas on the creation of earth - I would not want them to spend time explaining their ideas until they showed me sufficient evidence to warrant my expenditure of time.

By comparison, most people on LessWrong I'm willing to give the benefit of the doubt and let them explain the idea, then go look up evidence to confirm whether it has a solid foundation.

Keeping in mind that tendency to auto-accept ideas told to us...