My wife's the MF shooter in the family, but she goes through long periods of not shooting, as a result a lot of out of date film. I know now to buy her film in much more limited quantities. We always buy new and cold store. In the past we've had numbers and words bleeding onto the film from the backing paper (Kodak), or a crinkly, static type of pattern from the backing paper (Foma). Not all the old film has backing paper issues, but it's a crap shoot. Shame, because the old film itself was fine. If me, I just use the old film for personal projects, and view any weird side effects, as part of the creative process, sort of like flare in an image. But you know these medium format folks and their big negatives, they want perfection! Currently sitting on probably 50-100 rolls of out of date MF. Not sure what to do with it; maybe put it on eBay with proper disclosure?