There is a video of an artist who does it very realistically. This is her demonstrating a drawing of a cat in photoshop. Yes, I'm a youtuber!

http://www.youtube.com/watch?v=VgcnN21Mllg

Sorry, I just realized she didnt post wording as she does with some of her other vids, but you can see her draw it, then use the smear tool.