Posted By: 
peter chaoGil,
Look at this way, I've been in the hobby for 20 years and have looked at probably 500,000 cards.  I know most of the Topps cards by the color of their borders.  I know which cards come centered often and which cards are commonly found off-centered.  The only advantage a card grader would have over me is maybe they a black light or some other instrument that would allow them to look at a card more closely.  But it is unlikely that the typical grader would have my hobby experience in grading a card.  In my situation it makes little sense for me to rely on their opinion as to the grade of a card.
The only reason I'm not grading cards is that I make $400/hr. practicing law.  I doubt if the grading companies can afford to hire me to grade cards.
Peter