I think the better question is how do you not have notes on any book, period? From CGC's own grading process page on the main site:
"The book’s pages are then counted and any peculiarities or flaws that may affect a book’s grade are entered into the computer. Some examples of this would be “a tear on third page,” “a corner crease – does not break color,” “a ¼” inch spine split,” and so forth. When the grader examines the comic, he is not able to see a previously assigned grade, so as to not influence his own evaluation. After determining his own grade for the comic, he can then view the Grader Notes entered by a previous grader, and he may add to this commentary if he believes more remarks are in order.
Another restoration check is performed before assigning a grade. If all grades are in agreement or are very close, the book will be assigned a final grade. If there is disagreement among the graders, there will be a discussion with other graders until a final determination is made."
HTF does this entire process result in ZERO grading notes???????????