I'm not talking about Twitter snark or HN snark where an all-out nerd war can happen in a snap and nobody really cares. I'm talking about
snark thrown in a Github issue.
How do you deal with that while maintaining composure but not totally ignoring the poster?
Ignoring the snark, you then see if the issue really exists/is a fair point/is something you care about, and you respond as you would to any non-snark filled issue.
I don't see a point in trying to provoke the person, or 'educate' them, just respond neutrally and professionally, or happy and chipper if you can do it without it dripping in irony.