How do us as collectors grade figures?

The C-system is utterly worthless because 1) everyone makes up their own levels (like in this very thread - "C-9 MINT", I'm sorry, what? Nothing below C-10 should ever be called mint. Very few people in this fandom seem to understand what mint actually means), 2) When you get down to C-1 and C-2, what the hell is the difference? and 3) Nobody ever grades anything below C-7 anyway.

I use pretty much the same system as Gok in my own collection Spreadsheets (We're nearly as anally retentive as each other! Who'da thunk it?), with this Legend at the top of every worksheet:

MISB - Mint In Sealed Box
MIB - Mint In (unsealed) Box
MOSC - Mint On Sealed Card
M - Mint: Never transformed, flawless.
NM - Near Mint: Handled by a collector only, no signs of wear
E - Excellent: Slight signs of wear only
VG - Very Good: Mild wear to paint/stickers, no damage
G - Good: Shows mild to moderate signs of wear but unbroken
F - Fair: Moderately worn, may be damaged but not severely

My personal rules are no repro stickers or parts, original only. I don't give a damn if something's complete or not. With boxes/paperwork, they have to be in excellent condition - Nothing cut out, no rips, dents etc., maybe a slight flap crease if the flap stands straight but even then preferably not. With loose figures if it's not above VG (preferably E) I won't bother. The only time I make exceptions is if it's something exceptionally hard to find like a Diaclone/Pre-TF, Milton Bradley or Latin American release.

Edit: As an example, the red-faced Canadian Slag I picked up at BotCon (in-YOUR-endo) is only in Good condition at best, but do you have any idea how hard they are to get? Especially if you don't live in North America. Shut up Griffin it's not a bootleg goddamnit.