I have made a few orders on Alibaba now. My first order for a scooter did not work out at all (from Merlot Commerce and Dogebos Ltd). The item came in a crushed box and would not function. The seller would not replace any of the broken parts and offered the only recourse of shipping the unit back at my cost. Ridiculous.
Fortunately for me, I placed a small order first. I chose a different supplier for my next order, (Shenzen E-Fire Technology has been excellent so far) and I have placed several orders with them since.
I will continue purchasing through Alibaba. If you are going to use these folks, I recommend taking your time and ordering small first. Develop trust. China is going through a recession and some of their sellers are likely going out of business.