jschiwal, that worked like a charm. One of the other suggestions I got from somebody did indeed wipe out a lot of home "." files, so I did test this one first, and it worked great.
I'm saving your command line in a file I call "clean." Then I "chmod 777 clean" to make it an routine executable. Hmm. Guess I could move it over to cron, too.
Thanks, everybody, that's a genuinely useful discovery that will help me not to clutter up my computer and backup files.