I second that. It's not necessary about "lying", many candidates may drop a keyword as something they know, when really they have only heard about it instead of mastering it.
Some people also under-rate their skills, because they are very demanding to themselves (the bad ones don't know "sort" and want to re-implement their own sorting method in Python).
I pre-screen using practical problems that I have to solve every day, and when candidates know their UNIX shell commands that's usually a really good sign.