Echo chamber

The echo chamber effect can be detrimental for trust. Trust metrics should be designed to avoid this effect.

From Wikipedia:
 * For example, observers of journalism in the mass media describe an echo chamber effect in media discourse. One purveyor of information will make a claim, which many like-minded people then repeat, overhear, and repeat again (often in an exaggerated or otherwise distorted form) until most people assume that some extreme variation of the story is true.