The Grading Pyramid

Grading is a pyramid. At the top, you have the 10s. 10 means perfection and thus all 10s will be identical. As you go down the pyramid, grades are set for a variety of reasons -- 9s almost all look the same, but 3s, 2s and 1s have a huge number of potential flaws, including paper loss on reverse, creasing, corner wear, etc. What makes a card an SGC 30 could be a variety of factors that tell you nothing about the eye appeal of the card without looking at it.

Professional grading is not designed to reflect eye appeal. It is designed to point out flaws, often hard to see or hidden, in a piece of card board. When you see a clean-looking SGC 30, you actually know there are a lot of hard to see flaws. When you see a badgered up SGC 30, what you see is what you get. But not all SGC 30s will look alike -- in fact, at that level of the "pyramid" you will have a lot of different looking cards.

This becomes problematic when sellers try to sell a PSA 2 for what a previous PSA 2 sold for. Without comparing both cards, going by the number alone gets you nowhere because what you don't know about the previous card is whether the damage was similar or whether the eye-appeal was comparable. Sometimes you can get a pretty good deal on a nice looking 2 when a seller is willing to use a previous ugly 2 as a comparable. This is why they say, "Buy the card, not the holder."