One needs to make sure that the compressed air in a can is just air, a few can spit propellant at whatever your trying to clean, and some of this stuff makes Krazy Glue seem slippery in comparison......
Negatives naturally attract any dust or dirt within the general vicinity. If you get prints that contain a lot of dust or dirt on them, like this, then you should go back to the lab and demand reprints. If your scanning the negatives, always clean your negatives before scanning, clean the scanner bed and light source as well.
You gave me good news. I though the negatives were permanently scratched from the development.
I didn't scan them, it was a friend of mine. So i will clean them and see if they are clean.
In the next rolls, i already have a lab that develops and scans for a good price.