I don't perform the same work you do but I have ran into similar situations.  I perform land surveys so plats, past and present, are important information to me.  The last time I was in a BLM office I was asked by a person at the microfilm machine if I was a surveyor followed by a request to help them figure out the indexing system for plats and notes.  Their client has requested copies of all documents of record and the records went back to 1867.  I mentioned to them that over half of the copies they had were of a cancled federal survey and it had no legal of title merit.  Didn't seem to matter to either them or the client.  I figure that somewhere a person has heard the "charge" to get all documents of record, and they don't give any thought to relevancy.  Records cost money and sure as heck I would charge for them if a client insisted on having everything, relevant or not.