Brad Stone writes for the New York Times about a study on attitudes towards privacy and the inconsistencies of human behaviour:

"Our privacy principles are wobbly. We are more or less likely to open up depending on who is asking, how they ask and in what context."

In other words, in contexts where privacy is not perceived to be an issue, we are more likely to open up. Thus, "creating an informal online atmosphere, it seems, encourages self-revelation, even though an unprofessional site is probably more likely to pose a privacy problem than an elaborate, professional one."

While it's pretty common sense when you stop to think about it, the point is that most people just plain don't. Indications that we are one step short of a surveillance society on the internet don't seem relevant for everyday interactions on the social web, even when we get warnings like this one, that anything written online can not only be seen but can later be used for court evidence. A court in Ontario ruled that the nature of a social networking site is that its content is intended for other viewers, and thus admissible to court. Regardless of whether or not you live in a nation-state where free speech online is illusory, users need to be aware that anything online is ultimately accessible and preservable for later accessing.

Or, to put the marketing spin on this, as Robert Kozinets does: "Using informal, unobtrusively-obtained online conversations seems to produce more valid, more honest, more real, more multifaceted consumer opinion data than online or offline surveys. "