What is you opinion of record, CD, and book ratings systems?

As the question is posed.

My own thought is that they are inaccurate and help lead to seller abuse.  I tend to go with #4, "very misleading and difficult to trust". 

And I wonder, with records, how much of the root of this problem extends back to the grade terms coupled with their definitions by Goldmine in the first place? I wonder how much of the confusion would have been cleared up in the first place if these terms had been used:
Sealed. (Not all sealed records are mint.  They can be dish-warped or even scratched.  Goldmine went soft on this one.)
Mint Minus/ Near Fine (As currently defined)
Very Good (very good should be very good, no need for the +)
Good (As currently defined as "very good")
Good minus (Barely passing as "good")
Poor
Trash

I rarely buy CD's on line so I have no opinion.

The same can be said for book ratings. A book in good condition should be in good condition.
I've been in the book business for many years and I rarely see a book described as "good" that I would call good. That's just poor use of English.
I have a copy of AllMusic's Jazz guide that I bought on-line. It has many marking, underlining, and highlighting throughout, library stamps and stickers, several dog-eared pages, and the wraps look like blankety blank. It was rated "very good". I kept it because it's heavy and return shipping would have been more than it's worth. It's serviceable, I just wish it had been rated correctly.
And what the heck is "acceptable?" Does that mean the waste disposal or possibly the recycling center will take it?