Three things I have found.
1. You need to identify the agents from the real thing.
If you say you will visit in 2 weeks to look at the production in factory and get no reply. Almost surely is an agent.
2. Always use google translate to Chinese and back to English before sending emails. You would be surprised how the grammar can totally change the meaning. Sometimes 3 easy sentences. Somtimes 10 minutes to get one line correct. Just adding or removing an 's' from a noun can turn a good sentence to rubbish.
3. If you can't turn off the spam from a supplier, be VERY suspicious.
And I have nearly 2 ton of machinery on order, paid for. You need to overcome the language barrier - read that as grammar. Once this was done, all is smooth sailing for me.
Super X3. 3600rpm. Sheridan 6"x24" Lathe + more. Three ways to fix things: The right way, the other way, and maybe your way, which is possibly a faster wrong way.