Media, like most materials, is affected by temperature. When exposed to extreme heat or cold the media will expand or contract. If the media is immediately written while it is in this temporarily modified state the data will be stored in an area of the disk prescribed by format specifications. When the disk returns to its natural state, however, the data will be moved proportionately. It then might be impossible for a drive to read it.
Fingerprints can be quite damaging to a diskette.
This process might even take a day or so before it begins to cause problems. But it will cause problems. If diskettes are not handled properly it is actually possible to duplicate a disk and verify it, only to have it fail later has the media is broken down by the skin oils. We research our media sources carefully and only purchase media from plants that have very strict quality control procedures. In addition, much of the media purchased is actually certified a second time by an independent source.