I have gotten the occasional 'reality check' in a big way to where something unexpected might have woke me to a situation i had not been prepared for. This has happened in 1 or 2 scenarios where i didn't have access to enough information about the other party. I don't think it is common. Usually I have a pretty good idea or at least, yes, like OP said, something has seemed off before any confirmation.

And yes, i try to remind myself to have expectations of other people, I even went through a period to where i had to tell myself that it is ok to have expectations as i felt guilty to expect something / anything of others.