Counterfeits can be original parts that were scavenged from e-waste and remarked. In many cases, the counterfeit part is real, but its life history is unknown - That is, reliability suspect. It gets even worse.
If you have not actually seen details of what counterfeiters actually do -- I highly recommend finding a paper, a class or attending the next DMSMS meeting (Google DMSMS 2012).
BTW, this has been going on for over 30 years that I've been a degreed Engineer. The sophistication of counterfeiters and awareness are the only things that have changed.
The old empty parts are easy to find. Extensive electrical testing may be necessary to find false upgrades or used parts (and even then it may not be possible to tell electrically until premature failure start showing up). ESD walking wounded -- almost guaranteed.
How about counterfeit drugs and even pressure bandages? If you can sell it, it’s being counterfeited!
Are counterfeit chips getting any better as increased effort is directed to detecting them? I could imagine the possibility that eventually high quality "generic" chips that rob intellectual property owners of their proper revenues might emerge. Creative "generic" vendors might even shadow product recalls by the legitimate suppliers. Special techniques may be needed to find fully functional high quality "generic" chips. Finding the "fake" / mislabeled / non-functional chips is easy in comparison.
Usually you receive a sample quantity to verify the integrity of the supplier, these chips are authentic chips. But when the large orders are placed, chips arrive with the same form factor just nothing inside. Empty shells of BGA's, SOTs anything. Usually simple components don't offer enough margin to bother counter fitting. The fact that you actually get a component that looks like the one you should have is the problem, because then they are signed for an money is handed over.
It's hard enough to fab and get decent yields when you are the rightful owner of the right to fab the parts. This counterfeiting can't be for anything more than simple components, no? What do the counterfeiters do - steal the golden GDSII? Reverse engineer the entire circuit and layout?
The only solution to protect against counterfeits is to have 100% traceability and accountability of everything used in a product right from the manufacturer to distributor to retailer to the shop floor to the finished goods thru out the life cycle of the product right up to a stage when the product is scrapped.
if you make a party accountable for the damages then such infiltration of counterfeit parts will automatically have a check