Yes, you're right. There are a lot of fake batteries in the market, and yes, sometimes the sellers don't even know. There are plenty of guides and videos online to help spot fakes.
Yes, Sony does not technically make batteries anymore, as they have sold their battery business to Murata. However, new cells are still made and labeled as Sony.
Based on what I've received from Gearbest, all appear to be legit based on both appearance and performance, so I suggest you buy some cells from them.
Oh, one more thing. Don't try 35A continuous on a VTC5! It's about 20A at reasonable heat levels. This is still plenty of current for most applications.