Not the least offended, disappointed, or surprised when you don't answer my comments: you write something interesting, I respond, that's often a complete interaction (though it could go back and forth more).

For me to expect a "thank you," well, then I'd need to leave a "thank you" every time you or another friend posted something interesting, informative, or particularly amusing.

I don't mind if someone thanks me, either individually or, as one friend sometimes does, collectively for my replies, but I don't expect it. Either I'm commenting because a friend can use help or because I enjoy doing so, or both. And it comes around: my friends leave me useful comments too.