actually, the film is often not the culprit... but the glass.... there are two glasses that need to be cleaned that the reader touches all the time in threading the film... then there are two sides of a lens... and then there is the mirror on the inside of the machine.... all of these should be cleaned when the machine is serviced... and often none of them are... if you frequent the same place, make sure you speak up about this to the assistant... they should KNOW how to clean these things... it is not something that a service has to be called for after one KNOWS.... and there are certain tissues that are required for the lens so they should have this in stock... trust me on this.. the static from the film zipping thru will attract dust particles to these surfaces and need to be cleaned.... as they become more and more THICK, they smudge more and more and look like scratches... be agresssive in getting the machines in working order.... it is part of their JOB to keep the machines in good working ord...