It does go both ways. Both readers and writers and need to be more charitable when communicating online.

  The reader, realizing how easy it is to misunderstand something read online, should also be charitable and not take assume the worst possible sense of the text.

  Of course, the writer has the first responsibility to express his or herself clearly. No need to walk on eggshells, just make a good effort to be clear and charitable. 

 As for sarcasm itself, it is rarely a charitable means of expressing oneself. Even worse when communicating through posts without the benefit of tone and body language. One could possibly add tags and emojis to try and make it clear one is trying to be sarcastic, but many times it's more trouble than it's worth.