The success rate must be low. Simplistically, if the sticker is intended to identify "A and B" coins (of A, B and C levels within a single grade) the math would suggest you have a 66% chance of having an A or B coin. But it doesn't work that way. There could be an overwhelming population of 'inferior' coins within that grade, so perhaps only 10% are acceptable by CAC standards. Point #4 in their FAQ describes the challenge and their objective: https://www.caccoin.com/faqs/
This entire A, B, C distinction is new to me, but then again I am not an "advanced collector". Apparently this ABC stuff is common talk amongst dealers. To me a 64 is still a 64. The lack of a sticker doesn't suggest otherwise. And some 64's (for example) have always been better than other 64's. We all have different tastes. YMMV.... all that.
With a sticker, on the other hand, a small group of guys in New Jersey is making that determination for you. Some like it that way. Others already know a superior coin when they see it. They don't need CAC's advice... or the premium pricing that goes along with it. That was another of Jeff Garrett's points. He thought collectors willing to do their own homework (and grading) are perfectly capable of making that determination for themselves.
I've always been told that PCGS and NGC require 3 different graders to review each coin, and that 2/3 must agree on the grade, with a head grader who occasionally intervenes to settle disputes or gray areas.
Along comes CAC with a new idea. They'll add an exclamation mark to the previous work done by PCGS/NGC, saying 'of all the similar coins we've seen, this coin is one of the better ones'. Of course, that's their personal judgment. Again, YMMV. I know mine does. CAC will often bean a toned $10 Indian that I don't find attractive at all.
Other companies have tried to muscle in on CAC's action, like Barry Stuppler of Mint State Gold. He's one of the industry's most experienced dealers, and his "PQ" sticker is similar to the CAC bean. It's his way of saying 'this is a superior coin'... (i.e., buy this one!) https://www.pqapproved.com/why-pq/
Fair enough. And to my knowledge he doesn't charge for the PQ label either. It's just his own way of highlighting what he believes are superior coins. I can live with that. To me his PQ is more of a marketing tactic, not an independent revenue source.
Back to CAC. Where it gets sticky, according to Jeff Garrett, is that CAC is also a trading company. As such there is an inevitable conflict of interest because they are trading in the same coins they review and sticker.
In the end Jeff seems to question, rightfully so, what that sticker is worth. It's wonderful when you and I submit an unstickered coin and CAC puts the magic bean on it. Ka-ching! Money in the bank.... less shipping/insurance and CAC fees of course. But what if the coin already has a sticker, how much extra is it worth? Jeff says you'll pay, on average, 39% more. So for the same budget you'll only be able to afford 2 coins instead of 3... or something like that.
Some might also wonder -- after buyers pay a premium to acquire a CAC-approved coin -- what's left on the table? You know, for guys like us. In other words, does a CAC approved coin have as much future price potential as a less expensive one, or did that monetary upside go to the guy who first got it stickered?
Significantly, the founder of CAC, John Albanese, once said 'we're probably seen 90% (don't quote me on the exact %) of the better/nicer coins out there' -- or something to that effect. So he believes it's pretty slim pickings from this point forward. What does that mean? It means that most coins good enough to sticker have already been CAC reviewed.
Which brings us back to that original question, the expected "success rate?" If the above statement is correct (and John should know) that CAC has already reviewed most of the available premium coins, we can expect the future success rate to drop significantly.
Which obviously begs another question: Should we be as eager to submit coins if the odds are so low? Only you can answer that question.
Interestingly, we can submit and re-submit the same coin until the cows come home, it won't matter. Once rejected, always rejected. And as each buyer purchases that same coin over the years/decades they'll never know its status in the CAC database, that it was rejected 12 years ago. It will simply be returned with a 'thank you very much' letter.
CAC management maintains that results are kept secret to insure privacy. There's also another explanation. Call me suspicious but I think it's a corporate strategy called paying the bills.
One of the great things about CAC? You can buy a coin completely sight unseen and it's very unlikely you'll ever get a dog. And that works well for some people.