John Phoenix, whoa, hold your horses!
I'm glad you had more to say on the subject. I think " it would be a logical decision to limit suppliers to ECF-approved ones" was a little strong.
I think too there is a difference between ECF (or should be more correctly) ECF member approved and ECF registered supplier. The restrictions set for registered suppliers are designed to keep the vendor in a good standing not as a reputable vendor but as a member of the forum who does business here. Yes, they do have some wording about that vendor being reputable but this is not always the case. I think their criteria as applied to if a vendor is generally reputable, has good customer service and fair pricing is woefully lacking. There is nothing to force a vendor to live up to those standards, especially when ECF charges for the privilege of being on an esteemed list.
For instance, I could alert ECF to several vendors that have really high and unfair pricing - for the same products others offer. I seriously doubt ECF would remove these people from the vendor list because ECF is happy to make money on them and those strict rules have not been broken.
I understand you are assuming that these vendors because they meet ECF supplier criteria, that this at least means they must be reputable to some degree. I understand you need some yardstick to measure potential vendors by.
Might I suggest for all vendors ECF registered Suppliers or ECF approved suppliers as well as all non ECF vendors that you poll the body of customers who deal with these vendors and let the yea's and nay's fall where they may. On your site you have a list of vendors you use. Connect this to a poll that shows user feedback for each one. If the poll shows a vendor has a consistent bad rating according to the users, then remove them. In other words, let the users be the judge, not ECF Supplier criteria. I believe vaping consumers in general from all walks will be a better yardstick to judge who stays on your list. I also believe it would be more fair to all vendors.
Perhaps you could ask for non ECF vendors that people know are reputable. ECF members will give you tons. Weed them out in time if their poll results fall below a certain point.