If you look at the internet as an opportunity to clearly express yourself on a matter you find interesting or ask clarifying questions, then there is never a problem.

In other words, when you don't feel a need to change anyone's opinion about anything (I imagine mostly because you've tried one too many times and learned your lesson), then you are ready to have an interesting conversation :)

Everything else is just born out of emotions - boredom, being angry/sad/etc. As you get older, you learn to recognize when people are coming from an emotional place and you let them be. You reach out with minimal effort and if they don't come to their senses, you move on. No problem.