I recently purchased SanDisk cards off ebay. Obviously was a mistake. They turned out to be counterfeit. I ended up returning them and for not much more bought them from B&H.

On a related note I downloaded Crystal Marks to test the eBay cards but in the process I tested all my cards I purchased from legitimate retailers and was shocked how many of my cards under performed their specs.

In particular I have many Transcend gold cards that are rated 90 read/60 write. Some returned 50 write but others were in the 30s that's half of what they should be. But when I tested filming at 4k @ 100mbs they all work reguardless of their speed.

What are the return policies of cards that don't meet their specs? Does anyone speed test their cards and return them if they grossly under perform. As a matter of principle I feel you should get what you pay for but realistic if the card functions properly and does what I need to do it doesn't seem worth my time and effort...

I believe sometimes they post burst rates when they advertise the read / write speeds.

I believe sometimes they post burst rates when they advertise the read / write speeds.
I understand that but I'm also talking about the variance in performance between the same model of card.

The test I did run was 1gb sequential read and write which is the only meaningful spec for video

You should report it to Ebay.