In order to promote CriticalSpirit, CriticsShouldBeInformed. A critic who is ignorant is not a real critic, he's just in the all too common business of TitillatingEgo?.
As opposed to CriticizeFromIgnorance?.
And articulate... If you are going to be blunt and pushy, you better be able to make clear concise counter-points. Don't shoot at armies for being dirty unless your own guns are shiny.
Both sides should be "good and concise and informed and polite", etc. Unfortunately, we don't always get ideal participants. In fact, I'd suggest that nearly all contributors have at least one weak area. Traits include but are not limited to: