I think they mean they immediately know which button to press as in press the one that they're designing the pop-up around encouraging you not to press.

i.e. "that button is given far less emphasis and made less convenient to press, so it must be the good one."

I'd call that shitty. It's not that the design is good, it's that the above person has become so accustomed to navigating this shitty dark pattern that it has become ingrained in how they use computers.

Kinda like gaining the experience of knowing which download link is the real one on a website full of fake download buttons. The fact that we can pick out the real one with a moment's thought doesn't make that any less of a scummy design move.