I'll chime in with some experience I have.
Sites like Aliexpress and Alibaba are basically, as someone said, the chinese version of Amazon. I tried designing a few Shopify stores around the concept of drop shipping (many of the ads that show up on your facebooks are just that). People take products of their choosing from those sites, dress up the photos/ad copy/and video, and sell them on a drop ship basis here in the states and all over the world. Some are making boatloads of money. I pulled the plug on mine because I decided I hated being tied to technology and a computer.
Point being (while I never looked into RTT) the sites are legit in the sense that the products are real and in a lot of cases just unbranded versions of the same stuff we pay a lot more for once it's branded. Find a seller with good reviews and it probably can't be beat. What turns off a lot of people who look at the sites is the poor English, s*** pictures, crappy descriptions, etc. I'm sure, as with anywhere, you can find some bad sellers but with some leg work you should be good to go.
And damn it, I'm in the market for a RTT myself, never even thought to look there. I'll def be doing that now.
-Evan
Feel free to PM me and i'll be happy to share any more of my experience with everyone.