Often I see people try to give critical feedback in the comments section of a manga, or in other public forums. I would say most of what I see of that here on batoto is really well intentioned, and generally polite. High five for the awesome general population!
That having been said, I think that relatively few people in the world have been exposed to consistent high quality critique. It makes me sad to see the best of intentions turn into something hurtful or unproductive because of a few misplaced words. So here are some basic guidelines for good critical feedback I threw together.
Any time you criticise a persons work in a public setting, you make it very difficult for a human to respond to your critique in a non-emotional way. One of peoples higher level needs are the regard of their peers. (Check out maslow's hierarchy of needs, it's pretty cool.) Basically a person would feel the immediate need to 'defend' their work. Their intellect engages primarily in an effort to show that your critique is unfounded. If it is in a face to face setting, as opposed to a forum, it might actually engender fear and/or anger from the person on the receiving end.
Both of these emotions are seated in the hind-brain. The back part of your brain deals with fight or flight responses to stimuli. When fear and anger are stimulated, PET scans have shown that brain activity in the frontal lobe, the part of the brain which deals with higher cognitive function, significantly decreases. A person experiencing fear or anger, literally cannot think clearly. Thus the most even the most rational argument falls upon deaf ears.
So when making effective critique, a good first step is to think how you can make it as easy as possible for someone to actually hear what you are saying to them. There are a couple of easy techniques for this.
Obviously, not in public.
Lead with questions.
There is something less threatening about critical feedback posed in the form of a question.
Get permission.
Almost no one will appreciate or listen to unsolicited critique.
No pronouns.
The word's "you did this" will engender that feeling of being personally critiqued, instead of the work being critiqued. So talk about the work in specific ways, as if it was a separate entity. "I noticed on page three there was..."
Point out plenty of good stuff.
Excessively harping upon the flaws will cause people to do that defensive thing internally, even if they are outwardly trying very hard to listen.
If you offer a critique, offer a couple of suggestions.
"I noticed this, what do you think about this thing? Have you though about this?"
Do not negatively compare.
"You did this thing in this way, but you can clearly see Joe is better than you."
I think it is pretty self evident why this is absolutely detrimental.
These are some basic guidelines I follow for good critique.