I tend to upload "commercial/non-commercial" stuff.  And being a hobbiest, I don't much care if the item I download is "non-commercial.  The only exception is where my work is fan-art and based on a "restricted use" (a likeness of a copyright or trademarked item without explicit permission to use the derivative commercially) -- then I'm careful to list it as non-commercial.  I never worry too much about somebody lifting my stuff: saying non-commercial in order to prevent that is worse than useless unless you have money for lawyers.