Scratching can mean a few things, it is the 1. physical act of using your nails on a part of the body that itches, but it is also the 2. movement of a vinyl record under the needle of a record player. As part of this second definition there is also a hint of 3."making it up as you go along". Of these I think the writer means the first definition but could have a hint of the third

Scratching is sometimes used as slang for writing. Could mean be is writing about the art.

Hey Hey Pineapple, I think the author means that he is looking on things that he disapproves. :)