Rule for matching real folders

Hi.
I trying to create a drop-box that sends files to my server and then presents a link for me to share. To make it easy for others I want to compress folders. Problem is that os X mix up folders and files, example applications. In terminal the app is a folder, in finder the app is an app.
My question is: How do I match a rule towards all folders regardless if they are treated as files in os x?

You could try filtering with "Kind is not Document". "Document" is a generic classification for regular files. Note that things like aliases will not be considered documents either but it's a start. Otherwise, I think you may have to drop to a shell script and scrape the output of 'mdls' and look for "public.directory".

Another option would be to compress everything, file and folder alike.