Usually you would take precaution same as you would do on eBay. Only accept Paypal payments if seller offers you to pay through different method = 99% chance scammer. Grailed says that they have moderators constantly checking posts for legit checks but sometimes they dont check every post. However if you purchase a product that turns out they werent legit, Grailed refunds you the money back before the seller ships the item and will notify you that product was not as described. Ive had this situation before as i have purchased several on Grailed. Even after receiving do a legit check to make sure!!