The principle of charity says that you should try to interpret what people say in a why that doesn't make them a total moron. As far as possible assume people are rational, well intentioned and (I know this sounds funny) basically think what you think.
This is all very fine and it is very important, but there's also a problem: people are raging weasels. If people rush round demanding to be interpreted charitably they might be less inclined to accept genuine disagreement. Worse, there's an incentive to be vague and waffle on for ages in the hope that readers will simply chose an interpretation that they like and believe the author to be deep. Or that someone smarter will "see" the brilliant insight, clarify it and give credit to the original author.
Incentives should not reward vagueness ambiguity or hedging.