enrico's found another possibility elsewhere. A file edited with ISPF and saved with PACK ON would probably count as corrupt if treated outside ISPF as a flat file in an application program.
For an ordinary flat file, I don't think there is a utility to check its internal integrity. The format is so simple, I guess, if you can read it it is not corrupt, if you can't it is. Never had a corrupt PS myself, or even heard of one.
Any proprietary format file might appear "corrupt" if it has its own internal structure and you try to read it.