I found this article pretty interesting. I think this note on how to approach backtesting results is spot on. I personally have found myself susceptible to wishful thinking and confirmation bias, especially when potential profits are concerned.

I just want to emphasize at this point that the job of every serious trading system developer is not to try to find support for the result of a backtest but instead to try to discredit it. Unfortunately, exactly the opposite happens in most publications. For example, varying the moving averages and claiming that because the system remains profitable it is robust, is not enough.