Ubuntu 13.04 (though had the same issue in both 12.04 LTS and 12.10). Unity desktop (yes I like it, shush).
Anyways, when clicking on the dashboard there is a tab for 'Files and Folders'. I don't have any files on this computer that isn't porn. In other words, it displays the images there (as it's supposed to), but I can't have it displaying the porn for obvious reasons. I have disabled 'recent activity' and even added the folder it's all in to the 'do not record activity in the following folders'. I'm assuming that works but as I don't actually have any other files, it still displays them.
I don't want to have to make it a hidden folder because it's on an external HDD and causes issues when moving from computer to computer (I have other movies on it as well).
TL;DR: Get rid of the 'Files and Folders' tab in the dashboard. Is it possible?