My two rules to live by:

• Assume positive intent. Emotions, body language, etc. get lost when you reduce everything to just text. If it sounds mean or sarcastic but might be curious or genuine, assume it is the latter until proven otherwise.
• never attribute to malice that which is adequately explained by ~~stupidity~~ being uniformed. Yeah people are malicious sometimes. I still give people the benefit of the doubt.

That, plus when someone is obviously trolling or stirring something up for fun, don't feed the animals.