Agree with the no feedback on a problem or issue, whether it was solved or not.

But if we're gonna be completely petty here, the posts where someone shares a story or a joke and someone replies with "I heard that 8 years ago next Sunday, but yeah, it's still funny".  It always sounds like a put-down to me, whether it's meant that way or not.  Obviously the OP hadn't heard it before and wanted to share with friends.  It'd be so much nicer if the "I heard it already" folks would try not to be quite so condescending in their reply or not reply at all.