Porn collection put people off upgrading to Firefox 3
“In some cases users had intentionally hidden these bookmarks in deep hierarchies of folders, somewhat similar to how one might hide a physical object. Having something from your previous browsing displayed to someone else who is using your computer (or even worse) to a large audience of people as you are giving a presentation, is really one of the most embarrassing things that Firefox can do to you.”
Source: pcpro.co.uk