I can understand PDFs scanned and uploaded before 2009 or so having scanner "unknown"/blank- from what I gather, our API was a lot harder to use at that point, and entering a description or link to LoC, Sibley, BSB, ... or saying that one'd used one's own scanning equipment (etc. etc. etc.!) was just not supported. But right now, "Scanned by Unknown" just gives the impression that one's found the CD with the PDF of the music on it in a bake sale or on the street (Scanned by Bake Sale Dropoff... ? ... ok, no...
) (or book sale, but bake sale sounds better. you know those CDs.) - totally anonymous and unknown scanner. Of course, having a known scanning source has several advantages from the point of view of the administrator, the editors/other uploaders, and the "normal end-user": 1) there could me more music by that composer or of that kind where that came from. nice to be able to follow the link (if a link) and see...
2) if there's something wrong with the scan (missing pages etc.) one can go to the source (e.g. Sibley Library) and if their copy also has the problem (as usually- if the uploader didn't do some post-download tweaking, though with some scanning sources this tweaking often has to be done and can cause things to be lost accidentally, so that should be checked too... ! ) and mail the source library (say) to ask if maybe they might rescan the original. (Librarians in charge of scanning are to be commended for their responsiveness here and other ways - and I so commend them - thanks!!
)3) "Unknown" scanning place leaves open the possibility that one could be looking at a very questionable scan (some sources are much less - credible about identification, copyright status, etc. than others) - better to - well...
basically - etc.
I realize I'm not being clear in my angst here, and I also realize it's unimportant. But I figured I'd say something.
Of course, this all falls under the General Header "What's your hurry? Slow down! Take more time over that upload / composer-category creation - whatever. Less hurry. "