Iâm not sure itâs fair to say that all systems are locked down or bad. There are public knowledge systems and trading strategies/ideas that can be tested against historical data. I think the key is to look and see if it makes sense. If the deal is âbuy my system for $29.95 and youâll make $1 million in profitâ, then itâs not good. If itâs something like I get 10% of all profits you make off of my system that could be legit.