The inside is clean, but there were a few places checked with a pencil, which I erased. Depending on how you look at it, there may be some areas where the erasure marks are noticeable. Also, there are a few places checked with a marker or permanent pen. The text is clearly visible, so there is no problem with using it. I checked it several times, but please understand that even if there are any remaining unchecked marks, this is a used item.