I read a post not long ago about a member that posted a buying lead, specifically mentioning that the seller had to offer an escrow service for payment.
Now he was chasing branded items, and of course got no response because the suppliers and the scammers didn't want to waste their time with him.
I think the same tactic would work great for finding genuine suppliers of the type of products you are chasing. If the scammers know that you are not going to be an easy target, they'll shuffle off to fry easier fish.
What you should be left with is some genuine suppliers who have enough confidence in their product to offer you the escrow option.
Maybe not 100% fail safe, but not a bad option to get yourself on the page with I think.