It's not like selling gear is the most honorable thing out there....you can't exactly take back a underdosed bottle of Deca within 30 days if you have your recepit. This whole importing / exporting of illegal substances isn't monitored by anyone but the people in the "game". That being said if someone wants to make any kind of real money in this industry the basic business priciples that exist in corporate america still stand. The companies out there that make a lot of money....don't make money on initial purchases....it's the repeat business that keeps their pockets lined with money. You think the industry for Pokémon is still booming with repeat business? HELLL no...it was a fad, here and gone before any serious money can be made.
The key to making any real money in any kind of business is by keeping your customers happy and to keep them coming back.
What makes more sense:
10 customers buying 10 vials, getting scammed and telling all their friends and never buying again....
OR
10 customers buying 10 vials, getting good product, then not only will you get repeat business, but you'll also get the precious word of mouth advertising which will always lead to new customers.
If these people sat down and really thought about it....a quick score is never worth screwing over someone for.