The bug (with the dreaded WONTFIX) is at https://bugs.launchpad.net/ubuntu/+sour
I have added ",except:type:ethernet" to the end of its "unmanaged-devices" definition, however it may be that someone using Bluetooth or other unusual devices may just replace this file with an empty one.
In other news, I have found that apulse works for running Skype without PulseAudio, as long as ALSA is not trying to use PulseAudio. On Gentoo this means actually removing PulseAudio support, as opposed to having it inactive, however on distributions with binary packages that would be problematic. It happens that removing /usr/share/alsa/pulse-alsa.conf (and preventing it from being installed again) is sufficient.