To me. it's kinda like fishin'! I usually avoid dhgate and, like reeder, find wholesale-outlets more reliable and also cheaper. I had actually conducted this same experiment, except in more detail than D4m, but he beat me to the punch before I was able to put together a post to summarize the experiment.
I also found the same seller as he did, mr. yipyaniwhoever, bought the same type of description D4M did knowing full well I was not going to get a 7750 powered watch for $50. What I wound up with was a Tag Heur SLR Mercedes Benz a21j w/faux chronos, the type of watch our "trusted" dealers sell for around a hundred. I filed dispute, it went to arbitration and I got a partial refund.
My conclusion, you get what you pay for, or probably a little more if you find one or two dealers who are fairly honest - and there are some. From these more trustworthy dealers you can get higher-end items as well but they are about the same as our trusted dealer's prices so there's not much point in it. But, Alvinado is correct, you have to do your research. In my case I was curious and wanted a bag of cheap watches to play with. But for finding a hidden pot of gold? There are no $300 quality reps to be had for $50...
But, I do have a nice V5 DSSD and a vintage GMT on order - from two of our trusted dealers... ;-)