Having a well-developed marketing plan and understanding Web dynamics will answer this question. There is a very simple answer to this one. It seems like they are expecting a piece of marketing material to do their work for them, like a job hunter who expects their resume to procure them a job. The same concepts that apply to running an ad in an industry trade journal apply to the Web. And if they return, there is a better chance of response.
Response means success.
Try selling the steak, and not the sizzle. Keep it simple, see how that works. You may be surprised at the results. Internet users are way above average in intelligence, education and earning power. Until then, feel free to give it a shot, but keep your expectations of on-line commerce in check.