I don't keep that many pictures on my laptop. I'd rather they not appear while my laptop is sitting in public. While xfce-screensaver can be set to show a random screensaver, there's no option to filter which screensavers appear.
On Xubuntu, the screensaver is controlled by Xfce-screensaver. The screensaver files, or 'hacks' as they are known, are stored under the following directory:
/usr/share/applications/screensavers
If you open a terminal and type cd followed by the directory, you'll find your shell prompt in this directory. Then run the following:
# rm xfce-personal-slideshow.desktop
You may need root permissions to do this. Type sudo followed by the above command if you get a 'permission denied' error. And that's it!
A small idea
Perhaps in the future we can see screensaver 'playlist' support? As in, some way to select only a subset of screensavers to be the pool for 'random'. I'd like to select my top 10 or 20 and have it cycle through those, rather than the current 'all or nothing' approach.
Justification for screensavers in 2019
I usually set my screensavers to random. The Linux community's xscreensaver project has produced a wonderful and eclectic mix of screensavers; there are far too many available for me to simply settle for one! It is a peculiar collection of psychedelic and styles and computing throwbacks. Everything including fake error screens, TV test cards, ants in a maze, bouncing cows. It goes on and on.
I know that screensavers are 'redundant' with the death of CRTs and the advent of LCDs, but I'd rather my computer show off it's graphical prowess than show a bland blank screen when idle. Don't be drab.
Addendum - KDE and MATE
After reading this recommendation from the author of Xscreensaver, it is now the only locker & screensaver daemon that I will recommend on GNU/Linux.
However, as of 2021 I am using KDE on my laptop. KDE's lock screen correctly masks the display contents when I wakeup my laptop. MATE does not, when I used it the contents of my desktop were flashed for 1-2 seconds before the lock screen was presented. Evidently, this was a huge privacy problem. Unfortunately, KDE's locker does not support Xscreensaver's screensavers, so I'm stuck with a bland static lock screen. If I am sufficiently bored I will investigate how to switch it over to Xscreensaver. I really like colours and patterns. Why, why, why is everything so bland and samey now? Who judged and condemned fun on behalf of all computing?
Thankfully, my desktop which runs Void Linux happily runs Xscreensaver. So at least I can enjoy the visual overdose, the gfx showoff there.
Addendum dated 20/07/2021.
