A trust model is just a map of who trusts who, when and in what circumstances. It establishes authoritative integrity, meaning, you are actually trusting who you think you are trusting. It is not reputation although reputation can play a major role in deciding whose assertions to believe. Trademark, standard labels and anything that you can audit is believed to have some degree of this integrity, or people wouldn't act one way when they saw the mark/label, and another way when they don't.
To understand the contrast, consider what happens when you see a term on a label like "fun" or "new" or "more" or "clean" on a label. There is no control or trust model behind these words, so you dismiss them as propaganda.