I think that learning to speak respectfully to people, even when we may disagree or dislike them even, is a valuable life skill. I was not really taught this in life. Not by my parents, school, TV, or anywhere, really. We "hear" we are supposed to treat people with respect, but are not actually given practice in actual life skills with doing it. Actual tools. It take a LOT of practice, and certainly to me, does not come naturally.
At this point though, it's become habit to try to be as loving in my posts as possible, while still getting my thoughts across.
I have been talking on forums for more than a decade now and I think I have learned, through trial and error, many things about how I come across. How to think before I write, and how to not take something badly that was meant neutrally or even in a positive light.
Even as of last week, I took something meant in caring as a dig against me. Different cultures, ages and backgrounds can make one thing written taken completely wrong. So I am always learning.
For people that speak rudely, or are perhaps out to have 'fun' at another's expense....well, it is my challenge to still present a role model to the best of my skills. Maybe by being courteous to rudeness there will be a positive result. Maybe some of their walls will come down. Maybe they can find a safe place to learn better behaviors.
I know this is possible in real life, so why not in forums? I used to be an Outward Bound instructor, and i worked with adjudicated youth in extremely serious wilderness situations. Sometimes being respectful of someone who is acting out becomes a new experience for them. People are often used to getting negative attention as a result of their actions.
Showing that you can dislike someone's behavior, but still treat them like they are a worthwhile being, is often an extremely new and exciting experience for them. It can change many things for them going forward.