There is nothing wrong with backtested results. The problem arises when the data set that you are backtesting is also the one you developed the system on. So you end up with a system that can make money trading data it can "practice" on, kind of a Groundhog Day type deal. Obviously the proper way to test a system is to test it on separate data. I have developed many systems that looked great on three months data but bombed on longer periods.
A lot of people here say backtesting is useless, but I disagree. If a system can't make money on historical data, I'm surely not going to risk money on it in the future. Isn't that worth knowing? It's not necessarily a guarantee that the system will make money in the future, but it's better than having no data at all.
A lot of people here say backtesting is useless, but I disagree. If a system can't make money on historical data, I'm surely not going to risk money on it in the future. Isn't that worth knowing? It's not necessarily a guarantee that the system will make money in the future, but it's better than having no data at all.