I remember Kabuto raised concerns about this and a few other issues regarding
Commodore 64 games. Crackers can make you have to wait through an obnoxious intro and clear a cheat menu, and even beyond that might possibly introduce or remove bugs or change some timing ever so slightly so that a barely-impossible trick becomes possible. Plus with tape-loading games you have variances in how much loading delay was transferred...
But in the interest of getting as many good games on the TAS scene as possible, I think we could consider relaxing the "ROM must be good" rule in cases where it would be practically impossible to locate a non-cracked non-degraded copy of the original game. Perhaps the community could examine all the available copies before starting a TAS and come to an agreement on the cleanest one. It may not be 100% authentic, but what is?