The seller is listing an unusually large number of the same exact bag. This is a red flag because there are websites where you can purchase good-quality replicas, and I have seen these replicas listed on eBay claiming to be authentic.
Note that replicas are usually made of fabric, as leather is more expensive and therefore all-leather bags are less likely to be fake. (However, I have seen fake Coach bags made of all-leather. The all-leather fakes are usually very easy to spot – i.e. the quality of the leather is VERY poor, the fixtures are all wrong, etc.)
To have a taste of some of the Coach counterfeit you could find on the market, here are some photos of Coach replica handbags.