How does content marketing successfully develop brand loyalty, given that consumers are usually suspicious about marketing techniques?

If you make your content honest, it doesn't feel like marketing. For instance you can write a blog about when NOT  to buy your product. Marcus Sheridan has become very rich with this 'honest approach':

Content marketing is a softer approach to building familiarity around your brand. Nowadays, few consumers actually sit through commercials, or read printed newspapers, or scan the weekend classified. Instead, they are online. They are getting news from Twitter, watching funny ads on YouTube, and searching craigslist or other well known classifieds. Content marketing is meant to reach and engage consumers while they are browsing online and viewing stories via their social accounts. In answer to your questions: Are people suspicious of marketing? Yes, absolutely, if the content marketing attempt is pushing, selling, and company/product centered. Depending on the company's product or services it is possible to create engaging content that teaches or entertains without always selling. What is the consumers perception of content marketing? They probably aren't aware of the term. Consumers want an answer to a question. They Google it. If your company has been strategic in it's approach to providing valuable content, your blog post organically appears in answer to the searcher's query. Is the loyalty real and measurable? Yes and no. Loyalty is based solely on the unique consumer. It's typical for consumers to leave a brand they've been loyal too if they have one bad experience via customer service. When it comes to content creation you have to have a purpose and plan set into place so that it can be measured and tracked. For instance, use unique bit(.)ly links on Facebook, Twitter, Pinterest, G+, etc. to the same content so that it's easier to track where visitors are arriving from. Are people loyal to the brand or the relevant content? Both. The more relevant and quality content that a brand shares the more often a consumer visits. The longer a visitor stays on the website they are more likely to purchase or try the product because the quality of content has gained their trust.