AOUMonitor (All Users) is listed in my Login Items:
The file does not exist because I moved all the ScanSnap stuff off this Mac to another Mac, but for some reason this got left behind, and I’ve tried googling but cannot for the life of me figure out how to get rid of it, and it is completely annoying me beyond all reasonable proportions.
Any help or suggestions would be welcome.
(Hashtag: this is why I always do clean upgrades.)
Wait for Catalina? 
Unfortunately I’ve not run into this before, the only thing I can think of is reinstalling it, removing it, and then uninstalling it again - which is a rather ridiculous workaround.
I came to the same conclusion as @RosemaryOrchard
Use something like appcleaner (but I’m sure you did)
https://freemacsoft.net/appcleaner/
I’ve found that sometimes these apps don’t check off all files that have been found, so make sure that they are all selected when you remove things.
Just to be safe I have Hazel also check for anything left behind.
btw: it says “all users”
Maybe there’s still something installed under another user on the machine?
Or a process running?
There isn’t another user account in use on this Mac…
I’m fairly (99.99%) sure that what happened is that ScanSnap found a way to add their app to auto-launch for all users by writing to a .plist file somewhere, but that file might not be specifically for ScanSnap (because so far my efforts to locate it have come up empty).
So the only thing that exists is likely to be a line or two in one file… somewhere.
Yeah, I’m probably going to do a clean install of Mojave on this Mac. It’s a server, so there’s no real need for it to be running Catalina, which will just interfere with all my automations anyway.
Grrr…
I’d also suggest trying an app cleaner (I use AppDelete, which hasn’t been updated in years [the dev died] but still succeeds in pulling astonishing numbers of plists and associated files when I delete an app), then reinstalling (if you need to).
I’ve seen cleanmymac remove broken startup item entries.
Maybe it’s worth giving that a try before doing a full reinstall?
