Unskilled and Unaware

Suspect.

Following up from my Two-faced post, here's a fascinating paper written by Justin Kruger and David Dunning. It opens:
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People tend to hold overly favorable views of their abilities in many social and intellectual domains. The authors suggest that this overestimation occurs, in part, because people who are unskilled in these domains suffer a dual burden: Not only do these people reach erroneous conclusions and make unfortunate choices, but their incompetence robs them of the metacognitive ability to recognize it.
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Well worth a read, if only for the bit about the bank-robber who believed he could render himself invisible to security cameras by rubbing lemon juice into his skin.