Trust is the key to relationship marketing. If you trust someone to do a good job, on time, and at the expected and you also trust them as a person, you will be much more inclined to use their services or buy their products again. You'll also be willing to refer them, or at least mention them, to other people looking for the same type business or service.
You can't buy trust and you can't gain it by advertising, though trust, dependability, and safety are common themes in advertising - though it may not be always obvious. For example, when a company states they've been in business for some number of years, the implication is, "You can trust us, we've been around for X years so we likely will be here when you need us."
When someone uses credentials, memberships, or associations in ads, the message is, "See, you can trust us, we've taken the training, got the license, belong to the group." This is borrowed trust from the credentialing or licensing organization or the professional or trade group."
An even more common use of borrowed trust is testimonials. Testimonials work in a couple of ways. If a celebrity gives a testimonial or just appears in an ad, even though we know they were likely paid for it, we are more likely to think, "Oh, well if I use it too I'll be cool like so-and-so (or whatever like whoever)." The second type of testimonial is from someone with whom the prospective client can identify - think of the weight loss ads that feature regular people, or the testimonials that state, "Just like you, I once blah blah blah. Then I found The Product and now my life has changed for the better." The obvious message here is that you can trust the product or service because someone just like you has used it and been satisfied. These ads are so effective, that in many cases disclaimers (even in small type) are required in the interest of consumer protection.
So trust is of major importance in advertising and marketing in general, but it's paramount in relationship marketing. And to gain others' trust, there are two elements:
1. Be trustworthy. If you are honest about who you are and do what you say you'll do, you'll earn others' trust.
2. Be trusting. While it's obviously not clear to them, people who are very open about their lack of trust of others are often not very trustworthy themselves. If you expect people to be trustworthy, and act and speak that way, others will assume you can be trusted as well. Please note - I'm not suggesting you leave yourself wide open or be naive. It's helpful to have good intuition or to exercise and strengthen your intuition, but at the same time have a general sense of trust and positive expectation about the universe and most people.
In short, If you trust, you will be trusted. Trust is the most valuable gift one person can give another. If you're not trustworthy, any efforts at relationship marketing will be pretty much useless.
