Obviously, vinyl is rather delicate, and, obviously, everyone has different ideas on how to grade vinyl, and why theirs is correct (sell on discogs long enough and you WILL find this out).
The amount of people who grade a record as VG++ is staggering. Unfortunately, EX isn't an accepted grading anymore, but it's much better to use that than adding and endless amount of +++'s to your grading, as it gives people a clearer idea of what condition the LP and cover are in, and it also means it is less likely to cause people to wonder if your + button is stuck, or if you fell asleep at the keyboard trying to work out what grading to give your copy of "Dark Side Of The Moon".
The following is, in my opinion the most accurate way to grade records. It's how i grade all of mine before i sell them, and it's also handy to keep this in mind if you are at a record fair or market looking to add to your own collection.
Prices do vary due to the pressing, rarity and condition, so also keep that in mind when grading to sell, or looking at something that's been graded that you want to buy.
Before i go into it, i'll outline the abbreviations that you'd see on pretty much any website that sells second hand records, yours truly included:
M = Mint
NM = Near Mint
VG+ = Very Good Plus
VG = Very Good
G+ = Good plus
G = Good
F = Fair
P = Poor
Here's a breakdown of what they mean and what to look for. In my opinion, buying anything online with an LP grading less than VG+ is asking for trouble, so if you want to have a look at that particular item, don't be afraid to ask for the vendor to send you photo's.
M / Mint:
An unplayed record that is absolutely perfect in every way. Should be used sparingly as a grade, if at all. Sometimes, even brand new, sealed items get damaged. ie: creased, cornered, seam split etc. in transit from my suppliers which automatically prevents it from this grading.
NM / Near Mint:
A nearly perfect record. A NM record has more than likely never been played, and the vinyl will play perfectly, with no imperfections during playback. Many dealers won't give a grade higher than this implying (perhaps correctly) that no record is ever truly perfect. The record should show no obvious signs of wear. A 45 RPM or EP sleeve should have no more than the most minor defects, such as any sign of slight handling. An LP cover should have no creases, folds, seam splits, cut-out holes, or other noticeable similar defects. The same should be true of any other inserts, such as posters, lyric sleeves, etc.
VG+ / Very Good Plus:
A Very Good Plus record will show some signs that it was played and otherwise handled by a previous owner who took good care of it. Defects should be more of a cosmetic nature, not affecting the actual playback as a whole. Record surfaces may show some signs of wear and may have slight scuffs or very light scratches that don't affect one's listening experiences. Slight warps that do not affect the sound are "OK". The label may have some ring wear or discolouration, but it should be barely noticeable. Spindle marks may be present. Picture sleeves and inner sleeves will have some slight wear, slightly turned-up corners, or a slight seam split. An LP cover may have slight signs of wear, and may be marred by a cut-out hole, indentation, or cut corner. In general, if not for a couple of minor things wrong with it, this would be Near Mint.
VG / Very Good:
Surface noise will be more evident upon playing, especially in soft passages and during a song's intro and fade, but will not overpower the music otherwise. Groove wear will start to be noticeable, as with light scratches (deep enough to feel with a fingernail) that will affect the sound. Labels may be marred by writing, or have tape or stickers (or their residue) attached. The same will be true of picture sleeves or LP covers. However, it will not have all of these problems at the same time.
G, G+ / Good, Good Plus:
A record in Good or Good Plus condition can be played through without skipping. But it will have significant surface noise, scratches, and visible groove wear. A cover or sleeve will have seam splits, especially at the bottom or on the spine. Tape, writing, ring wear, or other defects will be present. While the record will be playable without skipping, noticeable surface noise and "ticks" will almost certainly accompany the playback.
P, F / Poor, Fair:
Don't even think about dropping money on a record with this grading.
Since moving to Zurich, i've noticed how wildly different stores and vendors here grade their vinyl, and how different it is to how we graded them at the store i worked at in Sydney, and i find myself sticking to the gradings of how i was taught to avoid being disappointed or worse, ripped off. If you keep this in mind and remember that quality does NOT always reflect value (it should, in my opinion) you'll be on the right track to procuring your next second hand LP to add to your collection.