I happen to have received
I happen to have received two emails in one day from people upset with my sites. One is political: "I just clicked on your Guide to war link and I have to tell you this is the last time I will be visiting your site. [followed by a long political rant]".
The other one is also political, but in a different way: "Your site, specifically the portion entitled SoWhatsWrongWithTopicMaps, has led our organization to what I hope is an "unintended" consequence, namely, the possible cessation of work on implememting a well-constructed topic map. [... some ranting] If this has been your intent - to disrupt - you and your site have succeeded. If it is not your intent, I would urge you to consider modifying your content."
I am often surprised by how seriously people take the opinions I post online. Often they are really offended (for example, about this page).
Even my girlfriend has felt offended by some of the opinions I have posted about Colombia. I tried to tell her these are opinions, nothing more, and I may have changed my mind since, but she says many people consider what they read on a website as somehow written by an authority.