I have never seen look is used as a transitive verb. This is from the book Harry Potter. I don't quite get "Harry didn't look it, but he was very fast."
Here is an excerpt for more context.
Exactly why Dudley wanted a racing bike was a mystery to Harry, as Dudley was very fat and hated exercise -- unless of course it involved punching somebody. Dudley's favorite punching bag was Harry, but he couldn't often catch him. Harry didn't look it, but he was very fast. -- Harry Potter and the Philosopher's Stone, J.K. Rowling