Believing in people vs being naive?

I tend to believe almost everything people say, so I take the Mangago questions seriously. I recently got trapped in a string of replies to a question that I thought sounded like the person asking was having personal problems that they genuinely wanted answers to. This exchange ended with me finding out the question had been for show. This isn’t the first time something like this has happened to me and I’m not quite sure how to avoid it.