I use flexget with the main_file_only option, so that it only downloads the main file of video torrents. This works great for things that are downloaded via RSS. But whenever I download something manually it usually includes dumb nfo files, txt files, sample files, etc. So I made a script to run from cron that will scan all the directories in my torrent directory and delete all the files that aren't the main video files. It won't delete anything unless a directory size is 90% or more from video files, so it should be pretty safe.
Just putting this here in case anyone else finds it useful: