First off, sables were never really accepted.  The former versions of the standard were simply not very specific with regards to color.  It is only the current  version (approved in 1992) that has specific colors listed in each variety and the any color other than listed disqualification. 

Sables first began to appear in the show ring in the '70's (before my time).  There were many who did not like the color.  A few, I believe 3, solid sable champions were finished before a clause about the hair shaft being of uniform color was added to the ASCOB variety section of the standard (I think in the early '80's - again before my time).  Since the parti section was left untouched, and did not actually list all of the acceptable colors, it was left to the judges interpretation as to what where allowed colors.  So in the '80's you had the situation where sable & whites were shown, some judges put them up, some judges ignored them and other judges disqualified them. 

At the end of the '80's, the AKC Board of Directors wanted to make all of the breed standards follow a similar format.

This set the stage for the open discussion of the standard and the proposed changes that occurred at the 1990 Summer National in Atlanta.  (This was not before my time.  I was there and sitting in the front row.)  One of the changes proposed by the standards committee, chaired by Dr. Al Grossman, was to specifically list the allowed colors in each variety and add the disqualification clause for any other color.  In the new version proposed by the committee, neither the solid sable or the sable & white color were
listed in the colors for the ASCOB or Parti variety. 

It was the position of the committee and the ASC board that the then current version of the
standard did not allow sable & whites and judges that did not disqualify them were in error.  The membership in attendance expressed an overwhelming support of including sable and sable & white as allowed colors.  To compromise, the ballot that was sent out at the end of the year had two options, A & B, to vote on for varieties and colors  (I can't remember which option had what). 

One choice had sable listed in ASCOB and sable & white in Parti and the other did not.

Here is controversy point #1:  the ASC constitution specifically states that changes to the standard are to be presented where you check a vote "for" or "against", not check "A" or "B" as was done. 

Controversy point #2:  (Keep in mind that a 2/3 majority of the number of votes cast is needed to approve a standard change.)  There were several ballots returned with neither the "A" or the "B" box checked, in essence, abstentions.  According to Robert's Rules of Order, abstentions are not counted when calculating the total number of votes cast.  If the ballots with neither box checked are regarded as abstentions and not used in determining the total number of votes cast, then the option with the sable and sable & white color had the 2/3 majority votes cast for approval.  The ASC board counted the blank ballots in determining the total number of votes cast and the allow sable option just missed having the 2/3 majority to pass. Since neither option had the required 2/3 majority to pass (according to how the ASC did the counting), the section on varieties was left unchanged.

However, the new disqualification section, which had the any color other than those listed clause, did pass.  The AKC board refused to approve the standard with the new revisions because it now had an "any color other than those listed" disqualification clause, but the color variety section did not specifically list the colors. 

In late 1991 the ASC board sent out another standard change for approval.  The accompanying letter (and I wished I had saved it) said things like the AKC board insists we have this vote before they will approve the standard change, it is a mere formality, etc.  The letter never mention sables.  The standard section that was sent to be voted on with a "for" and an "against" boxes to be checked was the color variety section from the first ballot that did not list sables or sable & white.

The ASC board did not send out the section that has just barely not passed (or really passed if you go by Robert's), but the section that had what they felt was the correct interpretation of the colors allowed by the then current standard, ie, no sables.  Busy with the holidays, many ASC members just checked the "for" box and mailed it back in, never realizing until told later that they had just voted to exclude sables.  The vote passed with an overwhelming majority, the AKC board approved the new standard and it went into affect the spring of 1992.  Five years later a petition to change the standard to allow sables had enough signatures to cause a vote.  The 1997 vote had a majority, but not a 2/3 majority and did not pass.
"Rumors"

With regards to why the color sable is not accepted by many, a persistent rumor is that it got into the cocker gene pool via a beagle.  A black bitch named Jolee Buttons, owned by Ed McCauley of  Birchwood cockers, produced the first modern sable offspring.  Ed's father, with whom he lived, had a hunting pack of beagles, which is what started the rumor that Jolee got with a beagle to make the sables.  There are two things that make this rumor
ridiculous: 
(1)  the beagle pack was all female. 
(2)  the gene that makes the sable color in cockers is a different gene than the gene that gives the beagle it's color and saddle pattern.

There was some evidence that the board was trying to keep pro-sable people from joining ASC just before the 1997 vote.  When the board was not allowed to discuss the membership candidates behind closed doors, they tabled everyone's application to the next meeting.

As to what it will take to get sables voted in, my answer dead bodies.  Too many high mucky-mucks within ASC have in effect (if not in actuality) said "sables will be admitted over my dead body."  In all seriousness, until these people are out of the picture I do not see sables being allowed.  Now please, don't anybody take this as direction to go out and kill anyone!!

Fortunately, most of these people are already senior citizens.  I'm sorry if this seems negative and down.  As scarce as majors are, I sure wish sables were being shown!

Hope this answers your questions.

Evelyn Bravo