Fred,
While I have no doubt what you have related concerning your experiences and opinion is very truthful,
TPG statements and policies do not support your position. I was merely mentioning that the door seems to be left considerably open merely by virtue of what the tpgs indicate will not be graded (I assume on a supposedly consistent basis). While several types of cleaning are discussed on most
TPG websites, typically exclusions for grading/slabbing are such as:
NGC, from their "No Grade Booklet", (which they claim gives the full details for their non grading), after describing some types of cleaning, they state ".....Where such action is harsh, it will mar or destroy the natural luster and leave a scratchy, unnatural look. NGC will not grade coins it considers to be harshly or improperly cleaned."
also from the NGC "No Grade Booklet", "A coin that has been immersed in a diluted acid solution (or, commonly referred to as "dipped") and not properly rinsed will probably develop traces of DIP RESIDUE. This makes a coin have a cloudy or brown unnatural look. If this staining is severe, the coin will not be graded."
From the PCGS web site: "PCGS has a policy prohibiting the encapsulation of coins with problems such as: artificial toning, excessive cleaning, environmental damage, PVC damage, major scratches, or planchet flaws."
Note that these tpgs (others have very similar statements) are stating that excessively, harshly, or improperly cleaned coins will not be graded. By no means do they indicate by those statements that ANY or ALL cleaned coins will not be graded. Since only specific types of cleaned coins are mentioned as being excluded from being graded, the only logical conclusion I see is that the other types of cleaning do not automatically disqualify a coin for grading.
To find examples of top tier slabs for coins which, by their criteria should NOT have been graded, search the web for info on 1894-S dimes, and you will find coins in NGC and PCGS (and one or two other) slabs that have descriptions such as "harshly cleaned", "noticeable spots", "lint marks", "multiple dippings", "impaired proof", "scratches", "planchet flaw", "significant mark on Liberty's cheek", and "circular cut on the obverse". The above descriptions are taken from the 8 known examples which are in slabs. Imagine how bad the Rappaport Specimen (9th) must be, as it reportedly would not certify at either PCGS or NGC. That would seem to nullify a "rarity" exception for slabbing, especially considering how some of the others are described and they were slabbed. NGC's "full details" No Grade Booklet has no mention of any exclusions or exceptions to the no grade criteria. I won't even go into the grades that "improved" as time passed, even as extreme as going from XF up to the 60 range.
I would think anyone who has had a submitted coin returned as "body bagged" for a light dipping or other "minor" problem, would have every right to be more than a little upset after seeing the problems some of those dimes have that did get graded/slabbed. Everybody's treated equally by the tpgs, right? Especially since the graders are not supposed to know who's coins are being graded. Personally I do not believe that, but that is just my opinion.
I used to work for a coin dealer for a number of years, and some of the coins we removed directly from mint packages and submitted to tpgs came back as "cleaned" or "artificial/questionable toning". We knew that definitely not to be the case. Interestingly, upon submitting those same coins a second time (and usually to the same house), about half or slightly more of them would be graded. These errors/inconsistencies occurred frequently enough that I personally would never make a submission to any of them unless I had a concern for authenticity.
Granted, tpgs (at least some) provide some degree of safety, especially for the novice. Possessing the personal knowledge to enable forming one's own valid opinion IMO has greater value than reliance upon someone's else's opinion. I would value a
TPG's opinion on authenticity (much moreso than their opinion of grade or other attributes). I always thought tpgs should slab everything, even the counterfeits. The service(s) have all been paid for, so why not? That way, a buyer would at least know if the coin was considered genuine or not, and opinion on cleaning/toning/whatever else could be noted on the slab for the buyer to take into consideration during a purchase. The reason I include counterfeits to be slabbed, aside from receiving the service(s) paid for, is that if even a small percentage of them remain in the slab, it would in effect remove that amount from the raw populations where the unwary could be duped. There are also instances, at least within exonumia, where the fakes are worth more than the originals. But, I suspect that a fair number of body bagged coins are resubmitted by the next owner, or the next one, and the tpgs would not want to eliminate these "extra" submissions.
Hopefully the above substantiates my earlier comments that slabbed coins do not necessarily prevent anyone from purchasing any cleaned coins. The severe problem coins, yes, there is protection (with a small number of exceptions), but from all "problem" coins, no. The way collectors in general (until somewhat recent history) believed cleaning coins was a completely acceptable practice, I believe the tpgs would have precious little to slab if they truly did not ever slab any coin that had ever been cleaned.