There is a great deal of information already available in their main lines of business with items of high volume, popularity, and resell value. A great example of all three would be the original set of collaborative releases between Nike and Off-White, called "The Ten." Many people have bought authentic pairs, and many, quite a few knowingly, have bought fakes. There is a large pool of information on the variability of both authentic and fake items. Often, experts can determine which sellers have factory sources in common, because the factories frequently do not sell directly to consumers.
People who know where this information exists, since it is frequently in a few different places, could read as much as possible and compile it into guides. My guess is that's what they have done, since it can be difficult to be an expert on everything. The bulk of their business probably also has to do with a small subset of the full market. I doubt they see many requests to authenticate, say, a pair of Carol Christian Poell drip sneakers, because they are low in volume and overall popularity. And sometimes the best source of information is rep makers and resellers, especially with pieces that are difficult to duplicate.
Fakes can be convincing, but they're frequently sorted into a couple tiers, and in some cases, fakes can only be spotted with a detailed examination of areas where the fakes are most likely to deviate from the originals. There is a fuzzy threshold for quality that is determined by the ability to identify these differences while someone is wearing the fake item.
People who know where this information exists, since it is frequently in a few different places, could read as much as possible and compile it into guides. My guess is that's what they have done, since it can be difficult to be an expert on everything. The bulk of their business probably also has to do with a small subset of the full market. I doubt they see many requests to authenticate, say, a pair of Carol Christian Poell drip sneakers, because they are low in volume and overall popularity. And sometimes the best source of information is rep makers and resellers, especially with pieces that are difficult to duplicate.
Fakes can be convincing, but they're frequently sorted into a couple tiers, and in some cases, fakes can only be spotted with a detailed examination of areas where the fakes are most likely to deviate from the originals. There is a fuzzy threshold for quality that is determined by the ability to identify these differences while someone is wearing the fake item.