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.

Somewhat related: I loaded your profile and then to your linked site[1]. I notice that you don't post your email address anywhere I saw. Is there a reason? I bet it's listed somewhere publicly (and that I could find it if I looked hard enough), but it might feel better to have it somewhat less public.

Privacy issues are tough to compare between people. Each person has a different, often inconsistent, scale. And the metric of choice seems to be how "slimy" something feels.

[1] Also, it may be interesting to note that I actually felt a little uncomfortable even doing that, in order to look for a counterexample to reply to your post with. To me, it felt like it could appear somewhat unnecessary. If it does, I apologize. So it's obvious that my personal scale might be a bit on the touchy side.

edit, formatting

There is a huge difference between people who are looking for explicit information and people stumbling upon information.

I agree with you that the information is simply there. But I think context is needed for every little bit of information. And maybe posting this on a very public forum like this will loose some context.

Edit: found the article: http://www.schneier.com/blog/archives/2010/04/privacy_and_co...