Expectation is the Mother of Disappointment

This might seem like common sense but sometimes we let our guard down when we meet someone new. Someone who appears honest and shows a lot of promise.
However, there’s no such thing as a perfect human and you’re better off judging someone on the basis their actual actions rather than what you expect of them.
It’s worth noting that when you set a very high standard for yourself, for instance on integrity and common decency, that’s your personal commitment. Do not, not for a second, assume other people will necessarily live by that standard.
Hence, expect the worst but hope for the best. If they turn out as you hoped, then take that as a pleasant surprise. If they fall short of your standards then it won’t be so shocking.