So yesterday I got reacquainted with how Xubuntu is all kinds of fubar. I did a clean 18.04.1 server install then xfce + lightdm. Lightdm started ok, but the the xfce de did not get initialized (stuck on the login screen). So I installed xubuntu-desktop on top. That worked...fugly.

After faffing around with xubuntu for a half hour trying to beat it into something recognizable and functional, I nuked it with a restored raw install .fsa (filesystemarchiver) + xfce + slim.

Slim's a fugly dm, but it launched the bog-standard xfce desktop no probs.