From what I've seen, if you add only sugar and no facts you'll be better at persuading people than if you mix the two, as long as you can hit their emotions correctly.
Calling it sugar also seems a bit disingenuous, since so much persuasion is based on guilt and shame.
Is that really persuasion though? I mean, it's used as a form of persuasion, yes, but how often do you see guilt and shame successfully persuade someone to another side? I think the prevalence of those tactics is what feeds the attitude that any form of debate will do nothing but further entrench each side in the initial opinion.