[Mithadan]

Getting a bit far afield from the original topic, but years ago there was a thread arguing that Sauron was misguided (a polite lawyer term) in permitting a pockmarked and cratered field that allowed anyone to hide to exist before his front gate. This thread touched upon the imagery as well and included a debate regarding whether the desolation before the Gates reflected the battlefields of France during WWI.

I don't think that the Dead Marshes were specifically discussed. I would agree that the visions in the Dead Marshes were images and nothing more; not dead or undead. The images likely were placed there for shock and horror value by Sauron to make them even more difficult to traverse.