But even more importantly, as a matter of simple politeness, it is a good rule to honor someone's choice about how much they reveal about themselves on-line, even if you possess the technical knowledge to dig deeper.
We're talking about rudeness vs. courtesy here. The world will not be a better place if your algorithm is simply to find out as much as you can about someone and then broadcast it in as public a fashion as possible without regard to the person's wishes.