Unfortunately there are copyright issues, but it would be cool to scan the books in Overstreet as examples, or even just the pages with all the guidelines, such as how big a spine split or how big a chunk can be missing in a given grade. I'm sure Overstreet would rather have you go buy the book.
A formula is tough, although I can see where this would be geared to the non-sellers as a handy tool, another little bonus that comes with your monthly fee. In my last post I was thinking about it more from a seller standpoint, so I spoke too quickly perhaps.
One thought, is instead of going through a series of questions for every book, you could have a "grading guide" tab on the My Collections page. One click & I can scroll down to see that VG/FN is the highest grade that allows a 1/2 inch spine split. Heck, I'd use something like that. If a customer thinks a book might be overgraded, he has an instant reference, and can explain to me that he wants to return a book because I rated it VF with a 1/2 inch spine split. Kind of empowers the customer if you think about it.
Alright, if I'm going to get in a little X-Box before I sleep I'd better cut out.
For a while, a group of us were working on a grading exercise were we would send books around, all grade them, then agree on a final grade. We would also scan the front and back covers, include graders notes, etc. Eventually, I hoped we would create our own online grading guide, with all of our own pictures, examples, and descriptions. It would have been much like the overstreet, except completely online. Unfortunately, we did not have enough interest, or time (myself included) to finish it.
The CCL grading wizard is useful, but obviously has it's limitations. Sure it can be improved, but just as a basic algorithm with questions about your book, it will never take the place of a grading guide that has examples of actual comics, notes to go along with the grade, as well as the specific flaws that go along with those grades. Even with a grading guide like overstreet, the grader still needs sufficient experience to take into consideration things not covered in the book, as well as recognize errors, like when they accidentally put a picture of a VG/FN book, next to a description of a FN comic.
One of the major problems with the grading wizard currently, is that it's WAY to subjective. Yes, we all know there's aspects of grading that are subjective, BUT there's also rules, as well as aspects that are easily quantifiable, like "1/2 inch spine split." Nothing subjective about that at all. It is what it is. But, using terms like minor, moderate, severe, just leaves too much open to interpretation. For example: to me, minor might be a 1/32 to 1/16 inch spine crease, but to someone else might mean a 1/4 spine crease. A drastic difference in interpretation, and a HUGE difference in actual grade. So, adding terms to the Grading Wizard that take out subjectivity, and allow users to quantify, would be a step in the right direction, imo.