I market solar-thermal equipment by showing which experience belongs to the proposed application, what a partner can actually do and whether a project image depicts something built.
I grew up in Agartala, where a distant supplier often arrived first as a brochure and a local introduction. The confidence of the printed page could exceed what the person presenting it actually knew. That did not make the product unsuitable, but it left the buyer with questions the sales story had skipped. My career has been about making those questions easier to ask. I have also had to recognise a campaign in which my own desire for a stronger story caused the same problem.
The most persuasive reference is the one a buyer can correctly place in relation to their own problem.