It is far too easy to fall into the casualness of the internet (almost pulled a Jewel there), thinking like people being semi-open about themselves means you can ask anything in a comment.
One thing I’ve always tried to do is maintain a certain level of deco rum - and by always, I mean since 2005. I had a surprisingly memorable incident wherein I offended someone with my more jovial persona on LiveJournal (ohhhh, LJ). Rather than be honest, they decided to let slip a private entry where they were complaining about me so that I could see the complaining.
It worked, shitty as it was, and I reassessed how I presented on the internet. Rather than be all up in people’s stuff, I tried to maintain a certain sense if open aloofness until I felt like I had an actual kinship with the person and could relax.
For better or worse, it’s a matter of being reserved and assuming that these people, even though you may have a connection (even slight) dies not mean you have friendship or trust.
The internet does not offer trust or familiarity. Do not assume either and treat people like your closest friend.
Don’t be a jerk on the internet.