You're misunderstanding what I am saying. That's why I gave an example after that particular question -- the fact that when I did my undergraduate science elective, I didn't quite understand even what the textbook was saying, so I couldn't understand anything I was Googling because I just simply did not understand the content.

You state your answer as if you don't expect a PhD student to understand how to research sources, how to understand when something is reliable or not. Reliability is not exactly the issue here -- even reliable sources can have improper information, as sometimes even the experts get it wrong (my professors often wonder how the hell some articles even get published). I'm questioning whether someone can know whether the reliable sources are even giving the correct information, or the information that the assignment is looking for, if you can't even be certain that you know what you're doing.