Posted By: 
warshawlawI have been collecting and dealing (off and on) since the 70s.  I don't think there has been so much a change in standards as (a) a hyping of "high" grades, (b) a growing spread in price between near mint and up and everything else, and (c) a general seriousness that was never present in the old days, which comes with the vast sums being paid for the cards.  
I watched the rise of slabbing with particular interest.  From an economic standpoint, the rise of grading put a huge burst of new money into the cards by making it possible to make a killing on old inventory, at least until the price guides caught up.  The idea was to spend $15 or so to add hundreds in perceived value to the card.  In my first graded card deal, I bought a lot of 1952 Topps cards for $177, had all of them graded, and sold one for $500, all within a few weeks.  I did this over and over with existing inventory and new acquisitions.  
This economic burst also explains the constant upward movement of the "desirable" grade from near mint to near mint-mint to mint.  For what, 20 years, the standard major collecting grades were nm-ex-vg.  The, we get grading and this new nm-mt grade (the "8") is the gold standard.  Now it is the 9 and 10.  I see the shift to the "9" as resulting from the number of 7 and 8 cards that came out of the woodworks.  It just wasn't exclusive enough for the auction houses to hype, so they found a new tool.  It is stupid, of course, which is why I have sold almost all of my 8 and 9 cards over the years.  I'd rather have 5 sevens than 1 nine.  
I have always held to the same relative standards:
mint: does not exist.  silly to discuss.
Near mint - mint: looks pack fresh and unflawed at first glance but has a little something wrong that you have to look for.
near mint: not unflawed, pack fresh, reasonably sharp, clean and without big flaws.  Mild O/C is ok, as are minor print spots.  no creases, no bad corner dings.
ex-mt: discernable mild wear on first glance, no creases, no major flaws.
ex: no creases, corners mildly rounded, mild wear
vg-ex: sharp with a hairline crease, or rounded corners with no creases.  mild to moderate wear, depending on the other conditions.  
vg: honest wear--creased, corners worn, etc.
g: abused but not wrecked.  Rounded corners, a major crease, moderate to heavy wear.  
f: card intact but has major flaws: heavy creases. stains, etc.  
p: filler.  parts missing.  
Now for my pet peeves:
any crease at all, whether you call it a wrinkle, or whatever, is vg-ex at best. Period
any stain or writing is vg at best.  Period.
any crease that breaks the card's color drops it to vg at best.  Period.  
Any centering worse than 25:75 cannot be better than ex-mt, and it better be a screamer for it to be ex-mt.  
a perfect card with 65:35 centering one way is near mint.