To be fair, the topics they get to speak about are usually very basic, so if they are related to their fields at all, I guess they DO know those things.
For me, this is why I can't really stand watching them:
I have never seen them talk about anything really new, or interesting.
In every TV segment, they start off from zero and never get very far, or into much detail.
I guess as actual scientists they do have their own research projects, or at least interests in more advanced topics. It would be interesting to hear them talk about that once in while. Or in general focus more on the open questions where the current science is done.