If we do get cheated, the cheater will, of course, take advantage of however we may be fooled, but that does not make us particularly vulnerable. We are also hard to read, and unresponsive to many normal social cues. I have heard of some huge losses by NT professionals who thought they knew better. Indeed, whole nations have elected con-men. Some of them are amazingly persuasive, almost hypnotic.
When I was first out on my own, I made a conscious decision to trust people as a default response. Blanche DuBois famously said "I have always depended upon the kindness of strangers" in "A Streetcar Named Desire." There are even people who are prone to seizures, and still ride transit, handing a card with "how to help me" to the likeliest person if they feel one coming on.
Trusting people long enough to give them a chance let me form friendly partnerships and do mutual co-operation, without which life would have been very bleak. Overall, the gains were much greater than the occasional losses.
People who live on the edge financially are not always able to repay loans, and they give priority to others who need groceries, but sometimes just a few more requests are enough to recover funds.