Oh, it gets worse...
It's one thing to have users "store" old email and files in the Recycle Bin or trash folder or whatever. There's enough of this lunacy going around to where I would guess that it's a small double-digit percentage of people (frightening!).
But it gets worse. Much, much worse.
We dealt with a vertical-market ERP vendor (now fairly dominant in their field) who for years would store critical local machine configuration files and scanned document data in subfolders of C:\TEMP. They would then have pearl-clutching, screaming fucktard shit-fits whenever an admin had the temerity (oh my!) to actually delete stuff in C:\TEMP. Eventually they knocked this particular bit of stupid off, but to this day they still do things that make my head explode...