It is true that there have been some fake ICCS holders showing up on Ebay (and elsewhere as well). Ebay's policy is that they "don't allow" coins to be listed with a non-authorized 3rd party grading name (eg PCGS, NGC, ANACS, ICG and I think one other). Any coins in ICCS or other holders are considered raw, and it is against their new policy to put a numerical grade (eg MS-65) in the title on "raw" coins.
I think this mostly came about from many, many coins showing up in slabs of no name companies that severely overgrade their coins. These listings often included PCGS or NGC trend prices with them, which created a pretty bad situation for new collectors who weren't yet wise to the fact that some grading "companies" aren't respectable at all.
Although no holders are completely tamper proof, ICCS should do something more on their holders to make it harder to counterfeit them. As it stands now, it isn't hard for someone to cut open the flip, remove the inner sealed piece and certificate, then reseal in a new identical outer flip. I like that CCCS adds a hotstamp to their outer flip, so that if someone were to do this, they would need to use a real CCCS outer flip which would show evidence of being tampered with when it was cut and resealed.
Also take note that hard holders are also starting to be faked... And that nifty coin certification numbers can be a really false sense of security. Check out this link for more info:
http://www.coinpeople.com/index.php?showto...mp;#entry347004