When you're diving, you need to look for an accumulation of defects. I start at the spine...if there are NO ticks...you might have a 9.8 but IMO finding one in a dollar bin is next to impossible. Then, look at the corners....if there are defects on one...it's probably not a 9.8...but you might have a 9.6 if the defect in the corner is minor. If there are one or two ticks on the spine. it's probably no better than a 9.4...as long as there are no more than maybe a couple more minor defects. If there are, you may already be down to a 9.0. (Yeah, anything between 9.0 and 9.4 is kind of like a grey area for me. Remember, its always an accumulation of defects. Although the corners are nice and the gloss is there from what I can see there is an accumulation of ticks...not one or two, and that's enough to knock it down. IMO this is no better than a 7.0/7.5 at best...but again, just an opinion and a generalization....maybe just enough to help you make an informed decision on whether or not to pull the trigger on what you think is a good one.
One final thing. It's quite possible there may always be some defects you either don't notice or you don't see. I still have that problem and that's why I can't win or even come close to winning these grading contests...but wow, you learn a lot. If they do have another coming up, make sure you take part. To me, the hardest part about grading is you don't have anyone experienced around you to let you know whether or not you nailed it. You can learn from your mistakes, but...you need to know you were wrong. If not, you'll just keep making the same mistakes and keep sending in those books you buy to get an opinion. There is so much knowledge in this forum from a lot of guys that really know what they're doing and yeah, I do know a lot about the hobby, but I'm still learning.. Just my 2 cents.
I don't know, what may have happened with this one. You noticed the spine ticks and thought wow, only one defect...it's gotta' be a good one. Try and look at (if you aren't already) as each tick being a separate defect. Hoping you can understand why it's the accumulation of defects that brings the grade down. Hoping that helps. Overstreet comic book grading guide would help...a lot.