I have had 'scratch' issues for years, at first my early M4 got the blame (NOT!), but now that I have an M6 the 'scratches' are still there. They are from handling the film after processing when the emulsion is still soft. Back when I began scanning my film processor (a very well known specialty outfit) would roll the film up and put it in a box for me to cut into sections later. After the film was cinched up it was always scratched. Then, I started paying the processor to cut the film and insert it into plasticine page sleeves. The first strip of film load into the page sleeve commonly had scratches, but the later strips did not. At first I thought this was from the scratches being made at the first of the roll, but no. The scratches were from the film being stuffed into the sleeve and being scratched while emulsion was still soft.
Air drying at least 1/2 hour post processing is necessary to get film that is safely handled for storage.
I always tell my processor to take his time with my film and I give him an additional day to accomodate me. I have very few scratches now and I commonly spend no more than 5 to 10 minutes spotting a 36 exposure roll! I've gone 10 frames at a time with no spotting at all after my scans!!
Wet film is VERY fragile, and any dirt in the developing machine will mar the film too. The days of squeegying off film with a wet sponge gripper are numbered with the newer emulsions that are made to be 'quick' drying for the sake of machine processing.