You're suspicions are correct IME. Direct marketing isn't an option for illegal substances, you have to know someone that knows someone, otherwise the police would just wander around all day waiting for offers. Also at the leaf nodes of distribution there is unlikely to be enough cash reserves to be offering free product or even small samples, the leaf nodes are generally users themselves.

Mostly it seems to be propaganda that drugs can be addictive after a single hit, which is complete BS.