Vinyl records grading scale


I am sort of new to vinyl and am building up my LP collection. A very prime source for it is the internet used market where appears to be sort of a grading scale system to rate condition of vinyl records on sale (G+-, VG+-, EXC, NM, etc). Is there any place I can refer to for the criteria or guidelines as to what to expect from the different ratings?
Also, what has been your experience buying used, and what is the lowest acceptable rating to get substantially noise free (tic/pops) records? Please let me know, thanks.
jmr
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How would you rate a new album which is not flat?
I bought one sealed. When I opened and played it, the fluctuation (ups and downs of the tone arm) is too much and I can hear the wobble.
If you bought a new album like that, would it be easy to return it for full refund? From ebay, Agon, private seller, or from record store?
02-26-07: Elizabeth
eBay code:
Mint: Still in it's original wrapper. (has plenty of mould, water stains, and the entire cover lays flat like a soup-bowl. But the guy who found it in a Salvation Army for $0.05 thinks it has never been played...
Near mint: same as above but has been used only a few times by a DJ scratcher. 99% of those grooves have never been touched.
VG++ :Hah hah aha ha... Same as near mint, but used by DJ after being in use at Juvi criminal lockup 'priviliges' area for 8 years.
VG+ : Even worse. Run over repeatedly by busses, after DJ dropped it in a hurry to his limo.
VG: Both Lp and cover chewed on by a dog playing "frisby" with owner who found it after busses did their thing.
GOOD: the LPs is possibly the one that belongs in what is left of the jacket. I may even be in one somewhat round chunk.

ROTFLMAO!!