Todd Rogers and Michael I. Norton, Harvard Business Review; Defend Your Research: People Often Trust Eloquence More Than Honesty:
"The study: Todd Rogers and Michael Norton showed subjects different videos of a political debate. In the first, one of the candidates answered the question asked. In the second, he dodged it by answering a similar question. In the third, he dodged it by answering a completely different one. When the candidate answered a similar question, subjects failed to notice the switch. They also liked him better if he answered a similar question well than if he answered the actual one less eloquently."
http://hbr.org/2010/11/defend-your-research-people-often-trust-eloquence-more-than-honesty/ar/1