I never been scammed because I simply do not trade or buy things from people that are not having a good feedback or not even have one these days its just so important to be on the look out.
Even if the trader is having a positive feedback, there is no guarantee that he will not try to con you. For example, in SR 2.0, there were some vendor accounts which had very good feedback, and still cheating their clients. I don't know what happened. Perhaps some scammer hacked these vendor accounts, and then used them to rob others.
no system is ever perfect and there will always be faults, hacks, scams,... everywhere, and all the additional information like trust rating on this forum are designed to give us some guidelines not the sure thing. when you see someone with green trust vs someone with red trust it is obvious which one is a
better choice and in the end we should always use escrow to reduce the risks of trading.