This thread on CA is a great example on how friendly criticism can help an artist correct and improve his work. Note how everyone respected this artist's original idea and theme and there's no insults or unnecessary meta comments. The critics are focused in helping the artist achieve his own goals. They could spot mistakes in the piece easier because they do not have a romantic image of the work like the artist, who often can't help to see what he wants to see, and some even know better how to do what he wants to do and gently nudge him that way.

If you have no consideration, and I don't mean pity or sympathy, but genuine curiosity and interest for the person or the values that person represent to you, your good idea will not integrate well in the person's mind, or worse, your bad idea will be integrated uncriticised and will become a viral meme, allowing the integration of more negativity. Remember you like to be seen and understood by who you are and so does everyone else. This is not the same as wanting admiration and praise for the sake of it.

Some people think cruelty is cool or a necessary evil. I don't mean "kick in the ass and whack in the head" language, which depending on the other person's personality and mood, can provoke laughter. I mean that popular belief that we have to tell others things they don't want to hear, that is, to hurt them, so they become better people. This is not true. It's when I hear what I want to hear that I'm helped forward and become a better person. Some people even go beyond that that and think that their place is to make others understand that they are idiots or think of them as idiots to be educated and try to hide their agenda with politeness.

The motto "No pain, no gain" has been grossly misunderstood and misused. It's not an allowance for cruelty. What it means is that often, leaving our comfort zones can feel unpleasant. Challenging ourselves to solve new problems is a problem in itself, because we can wrongly misinterpret the difficulty we face and mistakes we commit as failure and that will make us feel bad. But the eureka, discovering the ideas that solve our problem, will feel good.

Also note how the simple mechanics of the CA forum encourage art education. In a thread comments develop into a single conversation and the artist can continue to participate in it, posting the progress of the same work. It's also great for sketchbooking.