My Grading Scale:

M (Mint) : Pack fresh quality, mint card stock, may still have tiny speck of whitening on 1 or 2 corners.

NM (Near Mint) : Near mint card stock, a few tiny specks of whitening on edges and/or corners.

EX (Excellent) : Excellent card stock, if there are scratches they can hardly be detected, light whitening around edges and/or corners.

VG (Very Good): Very good card stock, light hairline scratches, light whitening around edges and/or corners.

LP (Light Played) : Light creasing, multiple light scratches and/or spotting, light whitening around edges and/or corners. 

MP (Moderately Played) : Moderate creasing, moderate scratches, bumps, and or spotting, moderate whitening around edges and/or corners. 

HP: (Heavily Played) : Heavy creasing, heavy scratches, bumps, and/or spotting, heavy whitening around edges and/or corners.

DMG: (Damaged) : Card is literally falling apart.