What I've found is that often times defined formulas and calculations work better than my instincts/feelings/predictions. Base on profits, my code is probably smarter than I am as a trader. Would adding statistics help?
If I had trust that the bot didn't have malware/wallet stealer/trojan/virus/key logger then I'd use it. It's not the idea of a bot that I don't trust, it's that I don't trust where the bot came from or what it actually does. If the bot comes with source code and you have the expertise to determine that it's "safe" then that's fine. But a free bot is probably worth what you paid for it. If it's a highly profitable bot, why give it away?