In this article in the WP, it is reported that older folks are much more trusting than younger people, and they often miss cues that broadcast untrustworthiness. This correlates with the fact that older folks are victims of fraud much more than younger people.

To see if older people really are less able to spot a swindler, Taylor and colleagues showed photos of faces considered trustworthy, neutral or untrustworthy to a group of 119 older adults (ages 55 to 84) and 24 younger adults (ages 20 to 42). Signs of untrustworthiness included averted eyes; an insincere smile that doesn’t reach the eyes; a smug, smirky mouth; and a backward tilt to the head. The participants were asked to rate each face on a scale from minus-3 (very untrustworthy) to 3 (very trustworthy).

In the study, appearing online last week in the Proceedings of the National Academy of Sciences, the “untrustworthy” faces were perceived as significantly more trustworthy by the older subjects than by the younger ones.