This happens in business all the time especially when making business investments such as office refurbishment. Like many business investments it's hard tell exactly what the real value will to the company until it has been completed.
We are always asked to believe the proposals and ideas of the people who want to sell us things, and unless we are experts in the field we are always vulnerable to being lead by the nose. That's why people who want to avoid gullibility must demand evidence that ensures they are not going to look stupid.
I found a good example of how to re-assure potential customers about what a service is likely to be like on the NJR Coolspace website. NJR Coolspace are a specialist office refurbishment company based in the West Midlands in the UK. They have gone to alot of trouble to get across to customers just what working with them is like. So if you are considering Office Refurbishment in the West Midlands or further afield you might check their web site to see what you think.
Two ways they do is through office refurbishment case studies and also through a office space and refurbishment testimonial. Both of these relationship marketing techniques are ways that businesses use to prevent a business relationship breaking down because one company has taken advantage of another.
Trust can only be built on evidence, so take a leaf from the business relationship book and make sure you have evidence of future intentions freely provided.