Personally I go both ways.
I try to post helpful and thoughtful (or though-provoking) comments, except when I don't.
There's a number of topics that have been thoroughly hashed, and re-hashed, digested and even excreted several times. For those, snarky sarcasm comes out. It's an on-line forum, and I sometimes respond as if my brother in law's string had been pulled and the normal guff starts out, and I respond naturally.
Hopefully the reader can tell the difference.