Smough is a crazy bastard, if you read his lore he actually did things like crush up his enemies/victims bones and use them to season his meals. He also wanted to be one of the Four Knights of Gwyn, but because he did crazy stuff like that he was pretty much told no, you're crazy.

I always found it weird how Smough smashed the hell out of Ornestein when he was still twitching, giving indication that he was still alive but barely, while Ornestein gently placed his hand on his friend's body to gain his strenght.