Comment 34 for bug 258936

I was having the same problem and have looked a bit more into what is causing it in my case.

By default theres a check for a PICTURES folder (note all caps), which triggers recognition as a "Picture CD", regardless of whether the device is a CD or not (which is a bit daft - fixing this would be the better solution). What makes this worse, is that on a case-insensitive file system (eg FAT), having a top-level Pictures folder is not very uncommon.

I hacked around this by commenting out the relevant section is /usr/share/mime/packages/freedesktop.org.xml (where it defines the mimetype x-content/image-picturecd). You can probably use the same approach to avoid other unwanted bars coming up in nautilus.