Gonna repeat myself, again, but his response reminds me of Anthony Weiner's response a few months ago. Weiner knew the picture was his, so he couldn't really deny it without digging the hole deeper, but he also couldn't figure out how the pic got out there into the public domain - so the whole thing turned into one big, confused clusterfark. He knew it was him in the pic, but he knew he didn't send it, at least not intentionally, so his reaction did more harm than good.
To me it looks like Cain is in a very similar situation.
