You are misunderstanding "errors." File system errors discovered by Disk Check are often reparable, however massive errors during Disk Check often portend physical problems with the HD.
This is checked by the maker's own HD diagnostics which check the actual surface condition of the HD rather than the file system which reside on it. In some cases bad sectors can be repaired or sequestered, but if not the HD is declared bad to prevent future data loss resulting from continued operation.