Quote from Exploiter:
I do pay attention to return kurtosis in my backtesting, though not as much as I do to skewness. I believe a low kurtosis is desirable, which is the opposite of fat tails. A return distribution with low kurtosis is one that is relatively predictable, with no outliers either positive or negative.
Skewness I believe is more important -- I look for a positive skewness, meaning that the outliers that do exist are on the upside, rather than on the downside. This is essentially a long option profile. In reality there's nothing inherently good or bad about any skewness, but I think many strategies that have a negative expectancy but fool you for some time into thinking they have a positive expectancy have a negative skewness -- they make small returns very frequently and then suddenly lose it all. Think selling deep out-of-the-money put options on stock indices with any risk control and heavily overleveraging it.