We don’t really supply people with scratch paper, however we do have a pile of full-sized paper that has been printed on one side that we’ve put down at the end of the desk.
I’ve heard some SAs recommend taking paper out of the printers in Reference, and that is NOT appropriate.
If students want clean copy paper, they need to go and buy some, but I don’t mind giving them our cast-offs if they truly just need some scratch paper.