People are people, peoples perception of "good" and "bad" is relative and contextual.
Take that in to account when building your expectations of people.
I personally try to take the approach that everyone is inherently selfish and will do what's best/convenient for themselves (and perhaps the people closest to them).
and i mean selfish as a neutral descriptor, not a derogatory term.
No expectations, no disappointment, but i know that's not a viable approach for a lot of people (and i'm not immune to the occasional hope of someone pleasantly surprising me).
I'm not saying i don't expect good things/behaviours to happen, i just try not to build expectations on that eventuality.