About a decade ago I was hacking remote printers that were stupidly addressable from the internet. This still happens a lot in small offices. It still brings smiles to my face thinking about all those "bad' print jobs I sent..
Honestly, it's trivial to break most of them. Whether it's to change a bit of code to forward a copy of all printed / scanned documents without anyone knowing or to just updating the control panel to display pretty much whatever you want - all remotely.