You don't need to train floor employees to spot counter fits, they just need to fix ratings to enable customers to make an informed choice. Counterfeit items work because counterfeit ratings keep them promoted in search results.

Ebay works on a trust system, feedback is good/bad/neutral with a short dialogue and rolling seller ratings over a few timescales to help users guage product/seller quality. It works reasonably well.

With Amazon you need to use third party tools to filter out the bots get a similar level of information, but you have to manually wade through a bunch of bad results.