Is hard to guess intent from a post: much easier to do it sitting around with friends where intent is more apparent. Something like 70% (the figure was from a training consultant so a little suspect) of the meaning of what soemone says is not in the words themselves but from non-verbal cues. (body langauge, tone, rhythm of speech, eye contact).
I think we should all keep Edmund Burke's advice in mind. The only thing necessary for the triumph of evil is for good men to do nothing.
The frowny face idea would probably be a fairly grown-up way for the community to signal displeasure.