It is estimated that up to 10% of prescription medications at pharmacies are counterfeit.
How many skis and boots that you buy online are counterfeit?
A lot of the high end clothing counterfeits actually come from the same factories and use the same materials as their non-counterfeit counterparts. You might get a different color zipper or stitching, or something like that, but in some cases they are equal quality. They use the leftover material or over-production and just sell it directly.
Obviously, that isn't always the case. In terms of hard goods, I would be curious about this as well.
I know in the guitar world there are "replicas" that are sometimes passed off for the real thing. They can fool some people, but anyone who knows their stuff will know that it is a fake. I have a buddy who just couldn't believe he scored a "real" Les Paul for his teenage son for $200!! I just smiled and nodded...as long as he thinks he got a good deal. I just feel bad for the person who his kid decides to sell it to down the road.