People don't generally stop and think about what they put in the trash. It's almost as if when they put something in the bin, it immediately becomes non-viable and unimportant. The problem is, for paperwork and computer media, the secrets held within don't go away when the trash is carried out. They remain, waiting.
The same seems to be true when people discard electronic equipment - like a computer or a hard drive - and they forget to wipe it. They assume that anything on there is of no interest to anyone else. But they are wrong.
Germany's O&O Software has completed a study which found that 113 of 200 drives it purchased on eBay still contained data. Perhaps in some cases people did not even bother to format the drives at all before selling them on, but even when people had remembered, it was a simple matter to recover lost data with recovery tools.
By running data recovery software on the drives, O&O uncovered all sorts of information belonging to the previous owners, including documents, e-mail and pictures, some explicit and very private. One drive, so it appears, was used by a German government body.