In his 21 November 2014 blog post, Dusty Corners of the Market John Cochrane seems to imply that certain areas of the market tend to be more resilient to the forces of arbitrage and efficiency.

The paper he provides as an example discusses the cross-section of asset pricing anomalies with respect to sorts performed on the cost to short. The intuition is that asset pricing anomalies should be more pronounced for difficult-to-short securities because would-be shorts-sellers are discouraged and/or prohibited from taking positions which might counterbalance the long positions. The evidence supports this intuition--many anomalies are related to the shorting premium.

I think we're supposed to interpret this as evidence for the broader intuition that pricing inefficiencies should be more pronounced and resilient for relatively ambiguous and under-covered securities, or there exists some barrier to market forces. Likewise, efficiency is expected to increase as size, liquidity, and coverage increase.

What are some indicators that a given security might be inefficiently priced? Other than the hard-to-short barrier, what are some are examples of limits-to-arbitrage?