I have had quite a few people over the years of collecting mohair teddy bears and animals ask "How to do you tell the difference between mohair and synthetic plush?"
I have found one solution to be pretty effective for individuals that have trouble identifying mohair from synthetic fabric easily that I have named the ash test. Pull a few fibers off of the plush item and twist them between your fingers together to make a larger piece. Take a cigarette lighter or match and burn the strands. A polyester plush fiber will burn with a crusty substance left similar to melting plastic simply because it is "synthetic". Mohair & other natural animal fibers will burn but leave an ash. Picking the remainders up after cooling and feeling them between your fingers and smelling is the best way to help identify the difference. A simple yet effective tool to help identify fibers for collectors and sellers from novice to expert. You can't always believe what a seller or owner tells you as stories passed down are not always correct. I've seen plenty of items where people have sworn they know the true history of an antique mohair item when in reality I saw it for sale in a new retail store the past ten years. I hope this helps some of you out there as an additional tool for identifying mohair.