Talking about film quality, I few years ago, 2-3 years ago. I enlarged a photo from slow speed film from one of the alternative manufactures.
Meaning not Ilford or Kodak. This film had "holes" in the emulsion. The coating was not even orsomething and there were white spots on the photo. Meaning there were dark spots on the negative. It was made from a 35mm film (x-pan camera I think it was) and enlarged to about 80cm on the short side.
The manufacturer/distributor was informed and knew about this problems as far as I recall, but they kept it quiet because they had a large batch and many were sold already. However on normal sized prints nothing could really be seen.