Extend your generosity.
When you’re in the audience and the speaker says “um,” mispronounces a word, or seems a little nervous, give them a break. As long as they are prepared, and they’re trying to make a connection with you, give them the benefit of the doubt.
If, on the other hand, the speaker seems to be taking your goodwill for granted, if they are casual, winging it, and glib, give them my contact information.