An olde, but a goody.
It's been such a long time since I've had proper cause to use Flickr in anger that I'd forgotten how to do this. I was sure it could be done and that I'd done it before, but searching (Googling/DuckDuckGoing) wasn't helping me (although this is such an old tip the info is out there somewhere): If you want to search for photos not containing a certain tag within the Organizer you just need to prefix it with a minus; However, it won't work on it's own, you need to do this in combination with a tag the photos will contain; This was what was throwing me so I'm writing it here to remind me for next time.
So this won't work (trying to negate the tag "rejects"):
But this search will work (assuming they all have the tag "film", which for me they most certainly do!):
I've just finish uploading my roll (one roll, sounds sad) of 35mm from last year. Now I'm on to the 120 stuff. It is remarkably slow going "processing" these photos (which is only adding titles and descriptions) as Flickr is slow on my archaic PIII with 128MB of ram, but does work (Flickr is obviously remarkably well coded). A selection of photos from this roll to follow here very shortly.