The Catechism is quite clear that rash judgment is a bad thing:
"To avoid rash judgment, everyone should be careful to interpret insofar as possible his neighbor’s thoughts, words, and deeds in a favorable way: Every good Christian ought to be more ready to give a favorable interpretation to another’s statement than to condemn it."
True enough, and it has to be kept in mind at all times.
But there are some limitations. If a neighbor offers to make my family a dinner, I will assume that he does so out of kind decency and not because he's a serial-killing poisoner.
I will continue to make this assumption even if a godawful smell starts emanating from his kitchen whilst he cooks.
However, charity does not require me to believe that the meal will be a good one once the eau d'skunk wafting out starts making my eyes bleed. Nor does it require me to believe that my neighbor won an episode of "Iron Chef." Or "Chopped." Or even "Hell's Kitchen."
In other words, just because a gentleman might be trying to play 3D chess doesn't mean I have to think he's Garry Kasparov. Much less imagine he will be immune from making some awful moves.
Just a thought.