Seems like, since using sarcasm comes across as mean, rude, etc is what causes the "misunderstandings," maybe just don't be sarcastic on an international forum where subtlety in text isn't apparent to everyone. The real ego seems to be in those who feel the need to be sarcastic (def: the use of irony to mock or convey contempt), as well as to defend its use.
"Why do I feel the need to mock someone in the first place?" should be the question, right?
Oh, wait . . . it's a free country/world/universe; if you don't get my "humor" then fork you; blah, blah, blah.
Every forum has this problem, but, IMHO, it's not really any misunderstanding of the sarcasm, it's just that sarcasm is intentionally hurtful--it is defined as contemptuously mocking someone, after all. What those using sarcasm deem as a misunderstanding on the part of the recipient is really just the recipient calling out those using sarcasm as unhelpful, mocking, rude, mean, etc.
What I find funny is that I teach 7th and 8th graders, and teaching them about the intent of their words/actions versus the impact of their words/actions is very similar to the arguments of when someone on a forum is "just joking." In fact, I use forum threads often to teach intent v. impact--prime fodder for thinking about how we relate to one another.
Post #29: Jcp2's second signature line stands out to me. If it's true for extremism, why isn't it true for sarcasm, etc?
{edit} Not a direct question to you Jcp2--just like your sig line, and feel it's a good example of what's being discussed.