From time to time somebody posts a painting that they like or make a comment about a particular technique that interests them. Some of those posters don't mind replies that lead to a knock down drag out debate while others don't want that at all, so misunderstandings can occur. Its really hard to tell, so I usually try to go by my mom's adage, "If you don't have anything nice to say don't say anything at all."
As for myself, I wish I had a circle of fellow artists with whom I could sit in a cafe and talk for hours, with the mutual understanding that its ok to really go at it, so long as it stays respectful and doesn't degenerate into insults.
Maybe it would be a good idea to have a category for that purpose. It might not be someplace everybody here wants to frequent, but it would be clear that if you post there, you can expect a debate. For example, the recent thread on hyperrealism - I just don't know whether its appropriate and respectful to the original poster to express strong opinions to the contrary or not.
Just a thought,