It's not about 'evil sellers' but counterfeit cards being inserted into the supply chain pretty early. You get them everywhere (just do a google search for 'counterfeit sd card samsung' or similar) and your only hope is (was) checking them immediately which is of course not sufficient any more if now counterfeit cards appear that do not fake capacity but look like genuine cards, show the capacity of genuine cards but are just fakes of lower quality.   Thanks for the num