Only a very tiny percentage of all coins in PCGS, NGC or other similar holders are likely to be graded higher by those services if broken out and resubmitted. A larger (though still relatively small) percentage, if broken out and resubmitted, are likely to be graded lower. This is because most of the coins on the market which the experts consider undergraded have already been resubmitted. Obviously, the more valuable a coin is, the more likely it is to have been resubmitted the optimal number of times to receive its ultimate grade.
To illustrate, let's imagine a coin which three graders out of ten would consider MS-65. The other seven would grade it MS-64. Based on probability statistics there is approximately a one in five chance that a random selection of 3 graders from this mix will result in at least 2 of the 3 graders grading the coin MS-65 thus insuring an MS-65 rating by PCGS or NGC. If the coin is worth $50 in MS-64 and $150 in MS-65, most dealers would just sell it in the MS-64 holder - possibly as a PQ But, if the coin is worth $300 in MS-64 and $1,000 in MS-65, chances are the dealer will resubmit it until the grading service finally grades it MS-65.
Needless to say, given the cost in time and fees of resubmissions, a dealer's ability to predict how other experts would grade a particular coin is very important to the bust-out game. Since the vast majority of coins would grade the same and some coins would grade lower only a few dealers can consistently make this a profitable venture. As an example, consider for a moment the above example. If one more person out of the 10 had graded the coin MS-64, this would have changed the odds to about one in eighteen, rendering most bust-out scenarios unprofitable.
Note: The consumer is probably not harmed by this, because the market takes this bust-out activity into account. Obviously, if a coin could never be broken out of a holder once sealed, MS-65's would be considerably rarer than they are now. The prices bid on the ANE system would be much higher as a result. Therefore, if a buyer purchases a coin based on the prices reported today on ANE (or any other sight-unseen bidding system), suffice it to say that he (or she) is only paying for a "low-end" coin that has most likely achieved its ultimate grade.