Comment 6 for bug 1202054

Issue partially resolved.

The 13.04 installation I mentioned was actually cloned from a 12.04LTS partition and I recall that I had problems with permissions
that stopped PostgreSQL from running. The command to change the permissions of the PostgreSQL directory under /etc/ is:

"sudo chown -R postgres:postgres PostgreSQL"

and there's a good chance I screwed that up and inadvertently created a human level user called PostgreSQL. This also meant that I could not delete user PostgreSQL... even tho it was disabled.

I just corrected this (chown) error and have now managed to delete user PostgreSQL which no longer appears on the login screen or the logout/shutdown screen.

Nonetheless, that does not explain how the the 13.04 install did not list PostgreSQL user on the login screen whereas the 13.10 install did.