How would you create the scratch file?
If you use tempname() or tempdir() and create files yourself in there, then the answer is NO, files in tempdir() are only removed whenever the operating system or user or system optimization software decides to remove them.
I do recall encountering one set of code that took care to put in an onCleanup() for a temporary file, but I have forgotten the context. You should consider using onCleanup() for this purpose.
