I have of course met candidates who don't know even the most basic constructs in a language they're supposedly expert in. But none of them were able to "talk the talk", especially when probed directly about problems they've run into and how they've solved them.
I want to be clear I'm not discounting your experiences and I'm also not trying to say you suck at interviewing or anything like that. What I am trying to say is that my own experience tells me there must exist questions that reliably expose this kind of candidate.