DHGate may be reliable, depending on what you buy.
For instance, I would not risk buying electronics. Especially easily counterfeited goods (and known counterfeit goods) such as Dr. Dre Beats, Shure SM57/58s, and Games.
I have always been under the opinion that DHGate was a counterfeit haven, and I have been very wary of using it. Most high name brands are definitely counterfeit. NBA, NFL, and NHL Jersey's are all counterfeit, but you can't tell the difference.
Use common sense in what you buy. Try to compare prices from DHGate to the same product on Amazon. People seem to think that they can make these products for less than $10 and sell them back for $400+ (in the case of Dre Beats). If the price different is greater than 25-30%, I would be wary in buying it.