This is not necessarily a scam by the seller but often a legitimate mistake. This is why we collect netsuke we enjoy. The market is being flooded with mass produced netsuke, often crudely carved from resin made to look like ivory. The really cheap resin can be rubbed against your clothes and will give off a slight plastic odor when it heats up. The newer stuff is more resistant.
Conventional method says to take a needle, heat it with flame and touch it to the resin.
The needle will melt a small hole, sending a curly stream of plastic out of the hole and creating a plastic odor. The newest resins are said to resist this test. This is why we collect netsuke we enjoy. Too often and erroneously thought of as the only legitimate material for netsuke. Elephant is the easiest to distinguish for the novice.