A little pet peeve of mine are the turd files that Emacs leaves behind all over the place.
For those that don’t use Emacs, when you edit files with it, it will keep a backup of the original file in a file with the same name, except with a tilde (~) at the end. The problem is that you have to manually clear them out. When you are jumping around in Terminal editing config files left and right, trying to get something working, you tend to forget where those files are. And yes, you can turn that off, but I like having the backups and yes, you can specify that it store its backup files in a common place but it makes it harder to recover files should I need to check the backup version, especially when I’m editing a bunch of files with the same name (index.php anyone?).
Since Hazel before version 4 only operated on actual folders/directories in the filesystem, it couldn’t really handle cases like this where the files are strewn all over the place. Now with Smart Folder support, you can create one to match all the turd files and have Hazel clean them up for you. Here’s a Smart Folder and Hazel rule you can use yourself:
One important bit about the Smart Folder conditions is that I use “Filename” and not the more readily available “Name” or “File extension” attributes as the ~ is tacked onto the end regardless of whether there is an extension or not.
And of course, no reason to limit it to Emacs turds. Go ahead and edit the Smart Folder to include whatever other poops you have on your system.