The reason they show on the 13.10 login screen is bug 1248541 had not been fixed - LightDM was showing users that accountsservice considered "system" (i.e. with a UI >= UID_MAX).
The reason they show on the 13.10 login screen is bug 1248541 had not been fixed - LightDM was showing users that accountsservice considered "system" (i.e. with a UI >= UID_MAX).