When I was starting out we used to stop off at a cafe run by this guy who had been in the windows game a while back. He told me an old name for window cleaners was "Diamond Scratcher".
What brought that back to mind was a new job I went to today - a 60's/70's self-build with big plates which had really thick frames which were varnished. And, needless to say, every time they were re-varnished, the old surface was sanded down . . . yes, you're ahead of me already - at least half an inch all round the edges was scratched. Cracking windows, but what a state they were in, a real sin.