In addition to what Mike Fila said, there's no proper authority over regulation with the printing of the class speeds. Each manufacturer tends to guarantee certain amounts of write speeds with each class however the result vastly varies from one brand to another.

I would avoid buying stuff from Hong Kong via internet and especially brand names without any warranty against workmanship. You save yourself a couple of bucks by buying stuff cheap but the quality of the product is literally thrown out the window.

Then there's pirated hardware, for instance you can get yourself products with misleading capacities. This does not specifically apply to only Kingston products but to many many other popular brands.