You need to remember one rule with film, the faster the speed rating the faster it deteriorates. Generally films that are 100 speed and slower, can, if properly stored, last a fairly long time, after they expire, especially B&W films. Higher speed films like 200-400, if they have been properly stored and are just expired can be okay. Ultra speed films, like 800-1600, can have colour shifts and fogging, even though they are just expired and have been properly stored. If your buying film from some clown on the Internet, you have no idea whether it has been properly stored, no matter what they say (people can and do lie).