I try to be fair and honest in my grading, and make every attempt to mention loose pages, stains, tears, binding damage, etc.  Sometimes I find that an item falls between two grades, in which case I will list it with a two-grade scale.

NEAR MINT - MINT: I rarely use these grades, except when an item is in truly exceptional condition.

VERY FINE: very nice with virtually no major defects.

FINE+: an even nicer copy, with minimal obvious defects.

FINE: a nice copy, flat with minor creases; may have some spine stress, but no prominent defects.

FINE-: better than VG+ but just a bit short of what I would consider Fine.

VERY GOOD+: most of the items I list fall into this grade; a typical read item with obvious defects as noted.

VERY GOOD: fairly well-read with an accumulation of tears and defects as noted; may be heavily creased or spine-rolled.

GOOD: a complete but heavily-read item item; may be missing pieces of covers, loose covers, rolled spine or other noted damage.

FAIR: a rough item, with many defects including tears. missing pieces, water damage, spine wear, etc.

POOR: no missing pages unless noted, but otherwise a pretty trashed item; almost any and every damage may be present.