I purchased from ali about 20 cams over the years and I never got any surprises. This is what I usually do:
1) Study description in detail especially the fine print, in most cases their description has discrepancies
2) Always clarify with the seller if that's exactly what they are selling
3) In some cases I also ask the seller for pictures of the box/label. If they reluctant to provide that, then I may look somewhere else
4) Reading feedback also helps, but not something I would rely 100% if it's too low.
5) Finally the price, if the price is generally too low then what others are selling then there is something wrong with it
6) If you did happen to order something and received completely different item then you can always dispute that, but I never had to do that for cameras
I do try to stick with reputable dealers when I can if the item is $$$. Actually most of Hikvision cameras I bought from one seller.
Btw, Hikvision made it a bit easier to identify Chinese & English models with new 4MP/2MP cameras. The model name is different. Any new 2MP/4MP models listed here will be English
http://overseas.hikvision.com/en/products_158.html