I have encountered a (for me) more serious problem with dbus-switchboard:

On the archive for scientific preprints, I had no difficulty reading pdf files either with the osso-pdf-viewer or evince by opening for example this paper by Stephen Hawking, http://arxiv.org/pdf/0710.2029, in the browser. Even though this does not have a file extension pdf, it is recognized as a pdf file and handled accordingly. But with dbus-switchboard installed, it no longer opens the osso-pdf-viewer or evince, because it's no longer recognized as pdf. It instead offers dbus-switchboard as a catch-all application, but that apparently works on file extensions only.

So I de-installed dbus-switchboard, and this now works again. Would you have an idea of how to make that also possible with dbus-switchboard or would that require a completely different setup not based on file extensions?

Btw, I noticed that the deinstallation is not restoring everything to the previous state. Before, /usr/share/applications/defaults.list was a symlink to /etc/gnome/defaults.list, and now they are separate with different contents. That doesn't seem to have any effects as far as I see, though.