As Richelle pointed out, DH Gate is not a supplier, but rather a directory of thousands of suppliers, so it's hard to review the site entirely.
I've used DH Gate a few times to make light wholesale purchases and most have been successful. I received the items and they were in good condition.
However, DH Gate is overrun with fake designer and brand name goods and as the majority of DH Gate sellers are China based, you can guarantee these are fakes.
Stick with non branded items, sellers with high feedback scores and safe payment options.