Because everyone else is being coy about it, I will tell you why it won't work.
I know because I've test thousands of strategy variations, automatically, using custom software. I also tested their inverse in each case.
The first reason is that the strategy simply may not have any predictive power at all, positive or negative, so given slippage, commissions and imperfect trading technique, it will work equally badly in both directions.
The second reason is that the profitability of a strategy is strongly influenced by the parameters of trade management (stops, etc.), and you need to adjust those independently.
You might very well find something that seems to work -- but odds are that the drawdowns are unacceptably high, or it happens to be a good curve fit for your limited dataset.
OK, I don't think I explained that very well, but now that I've spilled the beans maybe somebody else can elaborate.
You're not the first person to think of fading a losing strategy. But go ahead and give it a shot (on paper, please) and you will be slightly closer to trading enlightenment.
