Frank's model yields four conclusions. First, if cooperators and defectors look alike, then cooperators will be extinguished. Second, if cooperators and defectors are easily identified, defectors will be extinguished. Third, if mimicry has no cost or delay, cooperators will be extinguished. Fourth, if mimicry entails fixed costs of detection, there will be a stable mix of cooperators and defectors.

Russell Hardin, Trust and Trustworthiness, loc. 621