[passivate]

I used to think the same, but I received a sorta dodgy SD card from Amazon last year. By dodgy I mean that the graphics on the sticker seemed off compared to my other cards from Sandisk, and it was slower than advertised. It still worked just fine, and I don't want to imply that this is widespread, but it has happened to me.

[franklampard]

Can’t you just ask Amazon for a replacement?

[passivate]

Yes, they probably would have given me one, but I just didn't bother as it wasn't a huge issue for me - and also I realized it was dodgy after the return window had closed so didn't want to fight them on that either.