What don´t you know you don´t know?

We´ve all heard about the Dunning - Kruger effect back in that behavioural econ class and learnt that not knowing what we don´t know is a bad situation. Things go entirely south when we are certain we know something, but it turns out to be completely wrong.

Back in my first internship weeks in uni, when looking at a company I would often skip thinking through the business model, because I found it to be obvious. The pipe manufacturer sells pipes, the telco company owns cables and the automotive supplier produces parts. However, the only thing obvious was my blatant ignorance when asked about it by the bossman. I quickly learned to ask about the entire process of things and don´t assume, but inquire until I completely understand the matter.

Not the greatest example or learning here, but I´m really just copying of that other dumb thread. Maybe one of you guys has a good situation that you can think of, where you or people around you simply assumed something that was in fact not true. How do you systematically stop yourself from doing so? And for extra bananas what is the market/world currently assuming that is not actually true?