1. They pay me first without any escrow, with at least a trade value of 500 USD worth of BTC (Typically for something I am selling or auctioning).
Shouldn't it be the other way around? If someone pays me first then they wouldn't have a chance to scam so I can't judge their trustworthiness. However if I pay first and they deliver (or I deliver first and they pay later) while having a chance of scamming me - that proves trustworthiness, at least up to the value of the deal / risked amount.